'<■■ 



y .o 



\A 



* , <- <<V 










. % " ' 



4> * 



aV -k 



% f 



^ * 



-> 









■ v* ^ 






.-fc 1 



^ ..* 


















s # 






1* 






■ o* 









^ .^" 



'$% 



<6 V 






.0 







oH -r 



o* 



& ^ , 
c**. 














x 











-> 



O / 



'/- 






g q1 



* ^ 



5. *< • 



•%-. s- : 



\ 






o v 



o N 



'>- v? ; 







^ ■= 



= %< 



V 



V 






















ELEMENTARY TR] .TISE 



ox 



ELECTRIC BATTERIES. 






FROAI THE FRENCH OP 

ALFRED NIATJDET. 

MEMBRE DE LACADEMIE DES SCIENCES. 



TRANSLATED BY 



L. M. FISHBACK, 

OF THE BELL TELEPHONE CO. OF MISSOURI. 



.. Oft.. v 

'J A 




- ) 



NEW YORK: 

JOHN WILEY & SONS, 

15 Astor Place. 

1880. 






Copyright, 1880, 
JOHN WILEY & SONS. 



PRESS OF 

S. W. GREEN'S SON, 

74 Beekman St., 

New York. 









K> 



} Y 



PREFACE. 



The English translation of Mr. Alfred Mandet's " La 
File Electrique " scarcely requires my commendation to 
render it acceptable to the English-speaking community 
interested in the subject, since the author's name is so 
well kiown to electricians. 

This work will serve to guide the uninitiated in the 
choice and management of batteries, and even the profes- 
sional electrician may find not only new matter but even 
old material presented in a new form, and worked to new 
developments. 

Telegraphers generally will rind many of their fre- 
quently recurring problems solved in its pages, and its 
perspicuity will save both inventor and investigator from 
making useless experiments or errors, while at the same 
time the work offers to all new fields for careful research. 

Although the subject treated is so useful and interest- 
ing, yet this is, I believe, the first time it has received 
such recognition in English as its importance demands. 

The translator was happily fitted for his task, having 
studied under the direction of the author himself, and 
with whose sanction he undertook his task. 

Geo. d'Infreville, 
Electrician, Western Union Telegraph Co. 

Xew York, July 23, 1880. 



PREFACE TO THE ENGLISH EDITION. 



The work which we here present to the public is in con- 
formity with the second French edition of a book the first 
edition of which appeared in 1878, and which has been 
exhausted in less than two years. 

]S~o other treatise upon the "Electric Battery" has 
hitherto been published either in English, French or Ger- 
man. It has appeared desirable to meet this need, and to 
offer a complete guide to those who wish to thoroughly 
study or even to improve upon batteries, which are to-day. 
so extensively applied to different uses. 

The order that the author has adopted in his exposition 
is in some sense obligatory. Single-liquid batteries are 
the first, historically and logically, to jn'esent themselves. 
In connection with this first part are naturally placed the 
exposition of princijiles, definitions of terms, and the 
study of the phenomenon of polarization, wherein lies the 
whole difficulty of the subject. 

Next in order come two-liquid batteries, in which polari- 
zation is suppressed or reduced according to circumstances. 



CONTENTS. 



PAKT FIEST. 

Single-Liquid Batteries. 



CHAPTER I. 

INTRODUCTION. 



Definitions, 

Origin of the Name Pile, 
First Idea of the Battery, 
Properties of Amalgamated Zinc, 
Inconstancy of Simple Batteries, 
Battery Cells joined in Intensity, 



PAGE 

1 
1 
2 

7 

8 

10 



CHAPTER II. 




DESCRIPTION OF VOLTA's 


BATTERY AND ITS DERIVATIVES. 




Column Battery, 


. 


13 


Volta's " Couronne de Tasses," 




13 


Cruikshank's Battery, 




14 


Wollaston's Battery, 




15 


Spiral Battery, 




17 


Muncke's Battery, 




18 


Sand Battery, 


. 


19 


Nature of the Chemical Action in Volta's Battery, 


20 


Action of Air upon Batteries, 




22 



VI CONTENTS. 



CHAPTER III. 



GENERAL REMARKS UPON BATTERIES. 

PAGE 

Ideas upon Electric Resistance, .... 23 

General Remarks upon Electro-motivfe Force and Resistance, 24 

Electro-motive Force, . . . • . . 26 
Measurement of Electro-motive Forces, .. . .31 

Internal Resistance of the Battery, . . . 32 

Various ways of Joining Voltaic Cells, ... 34 

The Voltameter, . . . . . 38 

Secondary Currents, Polarized Electrodes, ... 41 

Polarization of a Voltaic Cell, .... 42 

Polarization in a Battery of several Cells, ... 47 



CHAPTER IV. 

SULPHURIC-ACID BATTERIES. 

Batteries with Carbon Electrodes, .... 49 

Manufacture of Carbon Electrodes, . . . .50 

Use of Carbon Electrodes, . . . . . 51 

Zinc-Iron Battery, ...... 53 

Iron-Copper Battery, ..... 53 

Other Combinations, . . . . . .53 

Smee's Cell, ....... 54 

"Walker's Platinized Carbon Battery, .... 56 

Tyer's Battery, . .-/■'. . . . 57 

Baron Ebner's Battery, . . . . . .58 

Batteries analogous to that of Smee, ... 59 

Remarks upon Polarization in the preceding Batteries, . 59 



CHAPTER V. 

ACID BATTERIES ANALOGOUS TO THAT OP VOLTA. 

Hydrochloric-Acid Batteries, ..... 61 

Nitric-Acid Batteries, ..... 61 

Various Acid Batteries, ..... 62- 



COjNTE^TS. 



vn 



CHAPTER VI. 

BATTERIES WITHOUT ACIDS. 

Sea-salt Batteries, .... 
Duchemin's Electric Buoy, 
Sea-water, Zinc and Copper Battery, 
Zinc, Iron, and Sea-water Battery, 
Accidental Reversing of the Current, 
Chemical Action in Sea-salt Batteries, 
Marine Batteries, .... 
Sal-Ammoniac Batteries, 
Bagration Battery, .... 
Carbon-Electrode Battery', 
Action of Air upon the preceding Battery, 
Chemical Action in Sal-Ammoniac Batteries, 

OTHER BATTERIES. 

Zinc-Iron- Water Battery, 
Iron- Tin Battery, .... 
Alum Battery, ..... 
Remarks upon Single-Liquid Batteries, 



PAGE 

63 
64 

67 
68 

70 
71 
72 

79, 



PAET SECOND. 
Two-Liquid B atteries. 



CHAPTER I. 

THE DAXIELL. BATTERY. 

Introduction, . 

Description of the Darnell, 

Improved Daniell Cell, . . . . 

Balloon Battery, .... 

A Reversed form of Darnell's Battery, 

Trough Battery, .... 

Conventional Furure, . 



SI 



101 
102 
104 
106 



Vlll 



CONTENTS. 



Muirhead's Battery, . 

Carre's Battery, 

Siemens and Halske's Batteiy, 

VarleyS Battery, 

Minotto's Battery, 

Trouve's Blotting-Paper Battery, 



PAGE 

107 
108 
109 
110 
111 
112 



CHAPTER II. 



GRAVITY BATTERIES. 

Callaud's Battery, . 

Applications of Callaud's Battery, . 

Trouve-Callaud Battery, 

Meidinger's Battery, .... 

Meidinger's Flask Battery, ... 

Kruger's Battery, ..... 

Sir William Thomson's Battery, 

Electro-motive Force of the Daniell Gravity Battery, 



118 
122 
123 
124 
127 
128 
130 
133 



CHAPTER III. 

GENERAL REMARKS UPON DANIELL BATTERIES. 

Amalgamation of Zinc m the Darnell, .... 134 

Copper-Plating, . . . . . . 135 

Irregularity of the Chemical Action in Daniell's Batteries, . 137 



CHAPTER IY. 



BATTERIES DERIVED FROM THE DANIELL. 



Marie Davy's Sulphate-of -Mercury Batte-ry, 

"Weakening of the Sulphate-of -Mercury Battery, 

Sulphate-of -Mercury Gravity Battery, 

Trouve's Reversible Battery, 

GainVs Battery, .... 

Latimer Clark's Standard Battery, 

Sulphate-of -Lead Batteiy, 

Weakening of the Sulphate-of-Lead Battery, 

Various Salt Batteries, 



140 
143 
146 
147 
147 
148 
150 
152 
153 



'ON 



TEXT'. IX 



CHAPTER V. 

ACID BATTERIES. 

PAGE 

Grove's Battery, . . . . . ■ . 154 

Chemical Actions in Grove's Battery, . . . 156 

Bunsen's Battery, French Model, .... 158 

Bud sen's Battery, German Model, . . 172 

Bunsen's Battery, Faure'js Model, . . . .174 

Electro-motive Force and Resistance in Nitric- Acid Batteries, 174 
Maynooth's Battery, . . . . . 175 

Daniell's Experiments upon the Size and Place of the Elec- 
trodes, ....... 176 

Chloric-Acid Battery, . . . . 177 

Chromic-Acid Battery, . . . . .177 

Various Acid Batteries, . . . . . 177 



CHAPTER VI. 

OXIDES IN BATTERIES. 

Peroxide-of-Lead Battery, . . . . 179 

Peroxide-of-Manganese Battery, . . . . 180 

Leclanche's Battery, ..... 180 

Leclanche's Agglomerated Mixture Battery, . . 189 

Clark and Muirhead's Modification of the Leclanche, . 193 
Electro-motive Force, Polarization, .... 194 

Chemical Action, . . . . . . 194 

"Weakening of the Leclanche Battery, . . . 196 

Practical Durability of the Leclanche Battery, . . 197 



CHAPTER VII. 

CHLORIDE BATTERIES. 

Chloride-of -Platinum Battery, .... 200 

Chloride-of-Silver Battery, .... 201 

Gaiffe's Battery, ...... 206 

Chloride-of-Lead Battery, ..... 208 

Perchloride-of-Iron Battery, .* . . . .208 



X CONTENTS. 




CHAPTER VIII. 




DEPOLARIZING-MIXTURE BATTERIES. 






PAGE 


Potassium- Chlorate and Sulphuric- Acid Batteries, 


210 


Bichromate of-Potassium and Sulphuric-Acid Batteries . 


211 


Chemical Action in the Bichromate Battery, 


218 


Application to the Telegraph, .... 


216 


Gaugain's Experiments, . . 


217 


Use in England, ...... 


218 


Fuller's Battery, ..... 


218 


Military Batteries, ...... 


220 


Grenet's Bottle Battery, .... 


222 


Trouve's Battery, . . 


224 


Byrne's Pneumatic Battery, .... 


226 


Agitation of the Liquid, ..... 


228 


Camacho's Battery, ..... 


231 


Delaurier's Battery, ..... 


232 






PAKT THIKD. 

Various Batteries. 



Dry Piles, 

Identical Electrode Batteries, 

Unattacked Electrodes in Batteries, 

Becquerel's Oxygen-Gas Battery, 

Coke-Consuming Battery, 

Gas Batteries, 

Secondary Batteries, 



235 
237 

238 
239 
240 

242 
243 



TABLES. 



Electric Conductivity of Solids, 
Specific Resistances, 
Conductibility of Liquids, 



253 
254 
255 



CONTENTS. XI 

PAGE 

Resistances of Liquids, ..... 256 

Dilute Sulphuric Acid, . . . . . .257 

Resistance to Different Liquids, .... 258 

Electro-motive Forces, ..... 259 

Remarks upon the preceding tables, .... 264 

Conclusion, ....... 265 



PART I. 
SINGLE LIQUID BATTERIES. 



CHAPTER I. 

INTRODUCTION. 



A battery, or pile as it is sometimes called, is an ap- 
paratus arranged to furnish a continued flow of electricity, 
to which the name of "electric current" is given. 

If one should wish to make a complete enumeration, 
it would be necessary to note : 

1. Hydro-electric batteries, to the study of which the 
present work is devoted ; 

2. Thermo-electric batteries, which have as yet received 
but few applications. 

It may be well to state, however, that batteries are not 
the only apparatus able to produce currents ; certain ma- 
chines produce effects exactly similar. 

OKIGIN OF THE NAME OF' PILE. 

The word pile, though not as frequently used as the 
word battery, is, however, more correct. 

The invention of electric piles is due to Volta, Profes- 



2 



SINGLE LIQUID BATTERIES. 



sor of Natural Philosophy at Parvia, and dates from the 
year 1800. 

One of the first that he constructed was composed of 
a certain number of discs made of zinc, copper, and 
cloth piled one upon another. In all courses of natural 
philosophy models of Volta's pile are shown, and 




Fig. 1. 

Fig. 1 shows the appearance of the instrument called 
the column-pile, which has to-day but an historical in- 
terest ; it is a pile of discs. * 

FIRST IDEA OF THE PILE, 



OK BATTEEY, AS WE SHALL HEREAFTER CALL IT. 

If you immerse a thin plate of commercial zinc into 

* This figure is a fac-simile of the first cut published of the bat- 
tery. The original cut is to be found in the "Philosophical Trans- 
actions" for 1800. 



INTRODUCTION. 3 

dilute sulphuric acid, a very lively action takes place ; 
the zinc dissolves, and a considerable quantity of hydro- 
gen is given off. It is indeed this process which is gen- 
erally employed in the preparation of hydrogen gas. 

But if, instead of ordinary zinc, which contains im- 
purities, zinc rendered perfectly pure by distillation be 
employed, the action takes place very slowly, the bub- 
bles of hydrogen remain attached to the plate of zinc and 
protect it from further action of the acid. 

If a thin plate of platinum, or a platinum wire, be 
now placed in the same, as soon as the two metals touch 
at one point the action becomes extremely energetic ; the 
zinc dissolves and hydrogen is given off, but from the 
platinum and no longer from the zinc. 

As soon as the contact of the two metals ceases, all action 
upon the zinc and all giving off of hydrogen are susj:>ended. 

This important experiment, due to De La Rive, throws 
a great deal of light upon all that follows. It is equally 
successful when you substitute for the platinum silver, 
copper, or even iron ; it gives the same result when the 
metals have their point of contact either in the liquid or 
out of it. 

It permits us to explain the difference in the action of 
the sulphuric acid upon pure zinc and injure zinc ; the 
heterogeneous particles (of iron or of other metals) found 
at the surface of commercial zinc play the same part as the 
platinum. You will observe, in effect, that the hydrogen 
is only given off within very limited points, and at the 
end of a certain time the surface becomes rough, which 
shows that the attack has been more active at some points 
than at others. 

Let us resume the fundamental experiment of De La 
Rive. 



4 SINGLE LIQUID BATTERIES. 

Suppose the two metals to have their point of contact 
not in the liquid but out of it, as Fig. 2 represents. 
The chemical action takes j^lace in the liquid, as stated 
above. 

It also takes place if, instead of bringing the two plates 
of metal into direct contact, you put one upon the up- 
per part of the tongue and the other upon the under part. 




Fm„ 2. 

You will experience a slight sensation like that of a 
feeble electric shock, and also a peculiar taste. 

If you place upon the dry part of the zinc a strip of 
paper dipped in iodide of potassium, and then touch this 
dampened paper with the platinum, a blue spot is imme- 
diately produced, which shows that the iodide has been 
decomposed and iodine set free. 

These experiments can also be made if you attach to 
the zinc and platinum two wires (indeed very long ones 
may be used), and operate with the two loose ends. If 
you place one of these in the neighborhood of a freely 
suspended magnetic needle, you will notice that the 



INTRODUCTION. 5 

needle deviates slightly from its north-south direction as 
soon as the contact is established between the two loose 
ends of the wires. 

These different observations prove that a singular 
phenomenon takes place in the two wires, which is the 
cause of various actions, physiological (upon the tongue), 
chemical (upon the iodide of potassium), magnetic (upon 
the needle). 

The analogy of these phenomena with those which 
electric machines with circular glass plates produce, and 
which were known long before, is easy to comprehend. 
It is said that an electric current runs over the wire, and 
one can see from its effects that it is continual. 

The two metal plates immersed in the liquid (Fig. 3) 




Fig. 3. 



are called electrodes ; the wires, long or short, attached 
to electrodes, and which permit the transference to a dis- 
tance of the effects produced by the battery, are called 
rheqphores. 






6 SINGLE LIQUID BATTERIES. 

The rfieophores are generally short, and often end in a 
longer wire, c ccc, to which the name of conductor is 
given. 

The name circuit of the current is applied to the 
whole, formed by the battery, the rheophores, and the 
solid or liquid conductor through which the current 
passes. In the experiments mentioned above, the tongue 
and the paper dipped in iodide of potassium formed part 
of the circuit. 

Every apparatus which produces a current is indeed a 
battery. However, the simple apparatus mentioned above 
(Fig. 3) is, to be more exact, a cell, or an element, of a 
battery, and a number of these cells grouped together is 
properly a battery. 

It is said that the circuit- is open when at any point 
whatever the conductor be disconnected ; all the effects 
of the current then cease and the current does not circu- 
late. The current is closed when the two parts of the 
conductor, which were separated, are brought into con- 
tact with each other and the current commences to flow. 

It is said that a battery is in short circuit when the 
conductor connecting its poles has a null resistance ; that 
is, when it is very short. We will frequently have occa- 
sion to use this expression in the course of the present 
work. 

It has thus come to be said that, in the conductor, the 
current flows from the positive pole of the battery (-[-plate 
of copper) to the negative pole (-plate of zinc) ; a transfer- 
ence of a peculiar fluid from one to the other of these 
points is thus implicitly admitted. Let us say, in pass- 
ing, that this way of looking at things, after having been 
abandoned in science, shows a tendency towards reaccept- 
ance with a few changes, so that the conventional Ian- 



INTRODUCTION. 7 

guage, which had not been changed, finds itself again in 
accordance with the theoretical ideas admitted. 

The cell formed of the electrodes of zinc and copper 
immersed in sulphuric acid is more particularly known 
under the name of Yolta ; by changing the nature of the 
liquid and the electrodes, you can obtain an indefinite 
number of cells which produce the same kind of energy. 



PEOPEKTIES OF AMALGAMATED ZINC. 

We have shown, in that which precedes, how differ- 
ently the pure zinc and the ordinary commercial zinc act 
in the voltaic cells. 

The result is that when pure zinc is employed there 
is no local current at its surface, and that the electricity 
which is produced passes entirely into the circuit be- 
tween the poles, and also that the hydrogen is given off 
from the copper. 

If, on the other hand, impure or commercial zinc be 
employed, the giving off of hydrogen takes place, for the 
most part, upon its surf ace ; there is reason to conclude, 
from this, that a very large proportion of the chemical 
action is lost for the production of the electric current. 

Thus, in the construction of batteries, the use of pure 
zinc presents very important advantages ; but the price 
of this material is almost fabulous, and it can almost be 
called a curiosity of the laboratory. 

Happily, a very simple artifice has been discovered, by 
which the properties of pure zinc may be given to com- 
mercial zinc. It suffices to amalgamate it — that is, to 
spread mercury over its surface in such a manner as to 
form a layer of amalgam of zinc. This amalgam is an 



8 SINGLE LIQUID BATTERIES. 

alloy, or, in other words, a combination of zinc and mer- 
cury. 

The experiment shows that the amalgamated zinc im- 
mersed in sulphuric acid diluted with water, is scarcely 
attacked, and if it be employed as the positive electrode 
of a voltaic cell, it occasions no local actions ; the giving 
off of hydrogen takes place entirely upon the negative 
electrode, of copper or platinum. 

In short, amalgamated zinc presents, for use in bat- 
teries, the same advantages as the chemically pure zinc, 
and with a few exceptions zinc should always be amalga- 
mated. 

INCONSTANCY OF SIMPLE EATTEEIES. 

All the cells of which we have spoken, formed of two 
electrodes immersed in a liquid, present an immense 
drawback ; namely, their action decreases very rapidly 
from the beginning of the action. 

The causes of this decrease are twofold, which we will 
analyze summarily here. 

The first is the loss of acid from the dilution. It can 
be easily understood that water acidulated in the propor- 
tion of 1 to 100 will act less energetically than water 
acidulated in the proportion of 1 to 10. This cause of 
the weakening of the battery is not felt until the expira- 
tion of a certain time, and it is easily avoided by adding, 
from time to time, acid to the dilution. 

The second is the deposit of hydrogen upon the cop- 
per. If the current be interrupted during a length of 
time sufficient for the freeing of the hydrogen, it will be 
seen, as soon as the current is again closed, that the in- 
tensity assumes its original worth ; it suffices indeed to 



INTRODUCTION. 9 

agitate the plate of copper in order to cause the gas to 
free itself and to give to the current its initial intensity. 

Constant batteries are those in which this second cause 
of weakening, called polarization of the electrode, is re- 
moved. The presence of the hydrogen upon the elec- 
trode opposes a double resistance to the passage of the 
current, a passive resistance and an active resistance; 
it is the latter that is properly called polarization of the 
electrode. To depolarize the electrode, is to provide 
against these resistances by suppressing the freeing of 
hydrogen. 

It is very important to comprehend perfectly every- 
thing pertaining to this question ; therein lies the whole 
difficulty concerning the improvement and perfecting of 
batteries. We will return to it in the course of our ex- 
position. 

Various reasons have combined to designate the posi- 
tive electrode as that one which represents the negative 
pole of the cell (zinc, in Yolta's battery), and negative 
electrode as that one which represents the positive pole 
(copper or platinum, in the cells which have occupied us 
up to the present). 

One of these reasons has been indicated above, which 
is that the current enters the liquid of the battery by the 
negative pole, and goes out by the positive ; in other 
words, the positive electrode is that by which the elec- 
tricity enters the cell. 

However excellent may be this reason and those which 
we will give further on for the choice of these denomi- 
nations, it is not to be denied that they are difficult to 
employ. In reality, this difficulty may be avoided by 
speaking of the positive pole and negative pole, when 
you want to designate the corresponding electrodes ; that 



10 SINGLE-LIQUID BATTEKIES. 

is what the majority of practical men do. But if you 
wish to employ absolutely correct and scientific terms, 
take great care not to apply them wrongly, as you will 
only arrive at confusion by an awkward research for pre- 
cision in the language. 

We find in the excellent book, " Darnell's Introduction 
to Chemical Philosophy," another denomination which 
ought to be employed more frequently than it is, because 
it presents the expression of a fact and does not depend 
upon theoretical ideas, which are always open to discus- 
sion. 

He calls the generating electrode that one which plays 
a part in the chemical action ; it is the zinc in the cell 
that we have considered. 

He calls the conducting electrode that one which is not 
attacked, and which serves, however, to complete the cell. 

The first can also be called soluble electrode. 

BATTERY CELLS JOINED IN INTENSITY. 

We have described above the most simple cell that can 
be prepared, composed of two electrodes of copper and 
zinc immersed in acidulated water. 

The cell of Yolta's column-battery does not differ es- 
sentially from this one ; it is composed of two discs, one 
of copper and the other of zinc, separated by a circular 
piece of cloth saturated with acidulated water. 

Two " rheophores," or copper wires, are soldered to 
these two discs and conduct the current to apparatus 
upon which it is to act. 

But as we have summarily indicated from the com- 
mencement, Yolta placed upon this first group of three 
discs (zinc, wet cloth, copper) a second group entirely 



INTRODUCTION. 11 

identical and disposed in the same order ; then a third, a 
fourth, and so on. 

These discs, in various quantities, the one at the top 
being of copper and the one at the bottom of zinc, con- 
stitute the battery of Volta. 

Volta discovered, by delicate means, that the force of 
the current increased as the number of cells was aug- 
mented, and made one of the most brilliant inventions of 
modern times. 

He thus showed that it was possible to add one source 
of electricity to another and to a third in such a manner 
as to obtain a multiple source of an indefinitely increas- 
ing power. 

Although three quarters of a century have passed since 
this discovery, it is not certain whether all of its resources 
have been exhausted, and it is probable that unlooked-for 
consequences may yet be brought to light. 

It is remarkable that he made at the same time an 
invention and a discovery ; he invented an apparatus, a 
machine, an implement, which has received and will re- 
ceive many applications : at the same time he discovered 
one of the most fruitful principles of physics, to which 
he opened a new road. 

If you should wish to show the increase of force of a 
battery with the number of cells or groups of three discs, 
the most simple means consists in causing the current to 
act upon a galvanometer or detector. The deflection of 
the galvanometric needle would be seen to increase in 
proportion to the number of cells ; that is indeed a funda- 
mental truth, verified by experiments at every moment. 

The copper electrode of the cell of Yolta (Fig. 3) is the 
positive pole, the zinc electrode is the negative pole of 
the cell. 



12 SINGLE-LIQUID BATTEEIES. 

When the cells are piled up or joined in intensity as 
in Volta's battery, the positive pole of the battery is that 
of the last cell, and the negative pole is that of the first 
cell. 

In order to give an exact definition of the positive pole 
of a battery, or of a cell of a battery, it is necessary to 
say that it is that one whence the current starts circu- 
lating in the exterior conductor, and that the negative 
pole is that one towards which this same current flows, as 
shown by the arrows, Fig. 3. 

To be complete, it must be added how the direction 
of the current may be recognized. The wire through 
which the current flows being placed directly over a 
freely suspended magnetized needle, causes the north 
pole of the needle to deflect towards the west, when the 
current flows from south to north. 

These preliminaries being established, we may enter 
upon the description of the principal arrangements of 
Volta's Battery. 



CHAPTER II. 
THE VOLTAIC BATTERY AND ITS DERIVATIVES. 



COLUMN BATTERY. 

We have described this battery in the preceding 
pages. We add that it may be vastly improved upon by 
soldering the disc of copper of each cell to the disc of 
zinc of the following cell ; all faulty contacts of the 
metal plates are thus avoided. 

The discs of cloth should be smaller than the metal 
discs. It is noticed, however, after a short time that the 
weight of this column squeezes out the liquid from the 
cloth; this liquid runs out over the edges of the discs 
and soon disappears, so that the battery rapidly weakens, 
and after a certain time produces no effect whatever. 

YOLTA'S " COURONNE DE TASSES." 

It is generally admitted that the column battery was 
the first one that Yolta arranged. This is, however, not 
correct ; the " couronne de tasses" was the first ; and 
according to us is much preferable. A series of glasses 
or cups were placed in a circle, forming a kind of a 
crown ; plates of copper and zinc were so arranged that, 
being connected at the top, the plate of zinc was placed 
in one cup and the plate of copper in the next. 

This battery is truly the model of all those existing 



14 



SINGLE-LIQUID BATTERIES. 



to-day, and will be our model for reference in the descrip- 
tion of others. 

It is interesting to note that Volta did not think of the 
column-battery until afterwards, and then it was with a 
view to produce an instrument that might be easily trans- 
ported into hospitals for medical purposes. 




Fig. 4. 



CKUIKSHAlSrK'S BATTEKY. 

Tin's battery is composed of a wooden trough, inter- 
nally coated with marine glue and divided into cells 
separated by metallic partitions ; these partitions are 
composed of two thin plates, one of zinc and the other 
of copper, soldered together. They are arranged in such 
a manner as to have all the plates of zinc on the same 
side and all the plates of copper on the other. The cells 
thus disposed in the wooden trough are nearly filled with 
acidulated water, and if they are water-tight the battery 
thus constructed is very satisfactory. 

It is not necessary to enumerate the inconveniences of 
Cruikshank's battery, which is no longer in use ; we 
would only point out the impossibility of changing the 
plates of zinc when they have been partially destroyed 
by the action of the acid. 



THE VOLTAIC BATTERY AND ITS DERIVATIVES. 15 



WOLLASTON'S BATTERY. 

The difficulty mentioned above is not to be found in 
the battery combined by Wollaston. 

The pairs of metallic plates (zinc and copper) are at- 
tached to a cross-bar of wood, which allows them to be 




Fig. 5. 

lifted out or immersed all at the same time in the glass 
vessels. 

This arrangement is excellent, and is still employed 
very frequently. 

Wollaston made another change in the combinations 
adopted before his time : he placed the plate of zinc in 
the centre and surrounded it with a thin sheet of copper, 
thus giving to the negative element a surface double that 
of the zinc. The reasons of this disposition are several, 
upon which we will remark : 

1. When two plates are immersed in a liquid, the 



16 



SINGLE-LIQUID BATTERIES. 



two sides facing each other alone combine in producing 
the current ; the other sides could be covered with an 
insulating coating without notably diminishing the cur- 
rent. In "Wollaston's disposition, the two sides of the 
zinc become active. 

To this it might be opposed that an inverse disposition 
would present the same advantages, and that a plate of 
copper might be placed between the two plates of zinc 





Fig. 5 



Fig. 5 



so as to make use of the two sides of the copper and only 
the half of the surface of the zinc. But as the zinc is 
subject to local action or waste, its size should be reduced 
to just that amount which is requisite to maintain the 
current required. There is, on the other hand, no dis- 
advantage whatever in increasing the immerged surface 
of the copper, as this metal is not attacked by the dilute 
sulphuric acid. 

There is, we repeat, an advantage in reducing the sur- 
face of the zinc as much as possible ; for when the battery 
is not in use and the electrodes, however, remain immerged 
in the liquid, the attack upon the zinc continues, although 



THE VOLTAIC BATTEKY AKD ITS DEEIVATIVES. 17 

with less intensity, and this dissolving of tn%zinc is pure 
loss. As this waste is evidently in proportion to the 
immerged surface, it is best to have the least possible 
surface of zinc ; or better, to have no part of that sur- 
face which may be useless for the producing of the cur- 
rent. 

2. "We have stated above that hydrogen is given off 
from the positive electrode, and that this polarization of 
the electrode was a cause of weakening of the current of 
the battery. 

If the hydrogen would free itself as it is generated, the 
production of the electricity would not be perceptibly 
diminished ; but it does not free itself — that is, not wholly — 
and what remains, tends to reduce considerably the inten- 
sity of the current. It is evident that the smaller the 
surface the more rapidly a certain quantity of hydrogen, 
being produced upon the positive electrode, will act ; in 
other words, the larger the surface to be polarized, the 
more slowly the effect of the polarization will be felt. 

This is the second reason given for the disposition of 
Wollaston, in which the surface of the zinc is entirely 
surrounded by the surface of the copper. We will re- 
turn to this subject farther on, in speaking of the action 
of the air upon batteries. 

SPIRAL BATTEKY. 

The two electrodes of this battery are rolled parallel to 
each other in the form of a helix, and separated by a 
tissue of osier ; in the centre is a wooden handle to which 
the whole apparatus is attached, and by which it may be 
lifted. It is immersed in a bucket of acidulated liquid 
and thus you have electrodes with very large surfaces 



18 



SINGLE-LIQUID BATTERIES. 



separated by a very short distance ; the interior resistance 
of the battery is consequently ranch reduced, and the 
quantity of electricity produced very considerable. 

This battery presents some of the advantages of that 
of Wollaston, inasmuch as both surfaces of the zinc are 




Fig. 6. 

used ; on the other hand, both surfaces of the copper are 
also used. 

Cells of this description may be joined in intensity as 
those of an ordinary battery ; but they were more fre- 
quently nsed separately. 

The spiral battery has indeed been entirely abandoned 
since the inventions of Grove, and Bunsen of Poggen- 
dorff (with bichromate of potash). 



MUNCKE'S BATTERY. 

Wollaston's battery being cumbersome and unwieldy, 
Mnncke, Young, the illustrious Faraday, and others im- 



THE VOLTAIC BATTERY AND ITS DERIVATIVES. 19 

asrined various ingenious arrangements for ioming a large 
number of cells in a small volume. 

In Muneke's arrangement, the parts where the elec- 
trodes of zinc and copper are soldered together are placed 
vertically; they are divided into two series, the one fit- 
ting in the other as Fig. 7 represents. 

This battery, and the one arranged by Faraday, which 




Fig. 7. 



differs from it very slightly, were employed for several 
years in laboratories, as the whole battery could be im- 
merged in one trough, which was very convenient. They 
are completely put aside to-day. 



SAND BATTEEY. 

This battery is composed of a trough made of teak, 
divided into ceils by partitions of slate or of wood ; to 
make it water-tight it is coated internally with marine 
glue. A plate of amalgamated zinc placed in one cell 
is joined to a plate of copper in the adjoining cell, and 
resting, at their point of contact, upon the partition ; the 
cells are then filled with sand saturated with acidulated 
water. 

This battery is to-day abandoned, but it presented 



20 SINGLE-LIQUID BATTERIES. 

many practical advantages. It was used for a long time 
in the telegraph service, needing no attention for several 
weeks at a time, and was much more easily moved from 
one place to another, than batteries wherein the liquid 
might be spilled when carried about. 



NATURE OF THE CHEMICAL ACTION EST 
YOLTA'S BATTERY. 

All the batteries that we have just described differ 
only in their arrangement from that of Yolta's ; in every 
one we find the zinc, the copper, and the water acidulated 
with sulphuric acid. 

The chemical action is very simple. Under the influ- 
ence of the water and sulphuric acid, the zinc becomes 
oxydized; the oxide of zinc uniting with the acid' pro- 
duces sulphate of zinc, and the hydrogen of the water is 
given off upon the electrode of copper. 

Thus, on one hand we have the dissolving of a metal 
(zinc) in the liquid, and on the other the freeing of a 
metal (hydrogen) which is extracted from the liquid of 
the battery. Hydrogen, although gaseous, is considered 
by chemists as a metal. 

It will be seen, as we advance, that the action is the 
same in nearly all batteries : dissolving of one metal, 
freeing of another. On account of its importance in 
nature and in chemistry, hydrogen will, of all metals 
with which we will have to do, be the one the most fre- 
quently freed under the influence of the battery. Far 
from presenting an exception to the preceding rule, 
this is a confirmation and a capital example. 

All our readers know that when they prepare hydro- 



THE VOLTAIC BATTERY AND ITS DERIVATIVES. 21 

gen gas for use in laboratories, they place small bits of 
zinc in an appropriate jar with acidulated water. 

Since there is an attack upon the zinc without the 
intervention of any other metal, it can be seen that in 
all the forms of Yolta's battery hydrogen gas will be 
given off and the zinc will be dissolved without closing 
the circuit ; that is, without the production of electricity 
by the battery. This is one of the greatest faults of 
these batteries ; they are consumed without doing any 
useful work, like a horse who stands in the stable and 
eats without working. 

In will be seen, in that which follows, that nearly all 
batteries present this same difficulty ; there are, however, 
a few exceptions, upon which we will bestow particular 
attention. 

The hydrogen given off under the chemical action of 
the battery appears upon the negative electrode of cop- 
per ; it is seen in the form of bubbles which rise and 
leave the liquid more or less rapidly. But in addition to 
these visible bubbles, there is a large quantity of gas 
deposited upon the surface of the electrodes and which 
is not seen. This invisible layer of gas is of great im- 
portance in the study of batteries, and produces, as we 
have already stated, the polarization of the electrode. 
¥e are thus brought again to speak of this phenomenon, 
so important in the study of batteries, and of which it is 
the most delicate point. "We have taken the opportunity 
of showing how this injurious action may be overcome, 
and how to obtain a partial depolarizatioii. 



22 SINGLE-LIQUID BATTERIES. 



ACTION OF THE AIR UPON BATTERIES. 

The air acts very favorably upon batteries on account 
of the oxygen it contains. 

At the time of the discovery of the battery, it was 
noticed that ordinary cells exposed to the air absorbed 
the oxygen, and that the current had a tendency .to stop 
when there remained nothing bnt nitrogen. But obser- 
vation shows that the effect is due, not to the action of 
the oxygen upon the zinc, but to a depolarization of the 
other electrode. In the cells of Yolta and Wollaston, the 
action of .the oxygen is experimentally demonstrated. 

It will be noticed that this depolarizing action is great- 
er in "Wollaston's battery, which is a new reason explain- 
ing the advantages of giving to the negative or conduct- 
ing electrode a considerably larger surface than that of the 
generating electrode.* 

* These remarks are only correct when concerning single-liquid 
batteries. There is no action of air in batteries totally depolarized, 
like that of Daniell. 



CHAPTEE III. 
GENERAL REMARKS UPON BATTERIES. 



IDEAS UPON ELECTRIC RESISTANCE. 

We have said that the most simple way of showing 
the passage of electric currents in a conducting body is 
to bring its force to bear upon a magnetic needle. 

Let us suppose that the conductor of a galvanometer, 
or of a simple detector, be inserted in the circuit of the 
current of a battery, and that the deflection of the needle 
be 25°, for instance. Now if the circuit be lengthened 
by the addition of a wire, the deflection will ' be seen to 
diminish to 15°, and if the circuit be made still longer, 
the deflection of the needle will not exceed 10°. From 
this experiment several conclusions may be drawn : 

1. The intensity of the current is less in the second in- 
stance than in the first, and less in the third than in the 
second. 

2. The influence of the additional wire being only 
passive, the reduction of the intensity of the current is 
due not to the decrease of the generating force, but to the 
increase of the resistance. 

These experiments give an idea of the resistance that 
conducting bodies offer to the }3assage of currents ; and 
they also demonstrate that the resistance of a conductor 
increases with its length. 

Yery exact and oft-repeated measurements have proved 



24 SINGLE-LIQUID BATTEKIES. 

that the resistance of a conductor is in proportion to its 
length and in inverse proportion to its sectional area. 

We will not dwell upon the demonstration of these 
laws, which are found in all works upon physics. It suf- 
fices for practical men to know the formulae of these 
rules which are constantly being applied. 

GENEEAL EEMAEKS UPON 
ELECTEO-MOTIYE FOECE AND KESISTANCE. 

In all machines in motion is seen a power or cause of 
movement ; and there are also resistances which tend 
more or less to slacken this movement or to stop it alto- 
gether. Let us take, for instance, a windmill. The large 
arms, under the pressure of the wind, cause the mill- 
stones to turn which crush the grain. In the working 
of the mill we see first a power, the wind, which pro- 
duces the movement. 

Then there is a resistance offered by the grinding; 
this resistance moderates the pace of the arms, and if the 
wind falls it stops them entirely. 

At first sight there are two mechanical elements ap- 
parent : the power or cause of movement, or motive force ; 
and the resistance, or work. 

A careful examination will show, however, that the 
resistance is complex, and that that offered by useful 
work, as the grinding, should be distinguished from that 
which is the result of the friction of the different parts 
of the machine in motion, and of certain secondary phe- 
nomena. All practical men know that a badly oiled rub- 
ber is sufficient to slacken the movement of a machine, 
or even to stop it ; all know the importance of friction 
in the different parts of the machine, and of the stiffness 



GENERAL REMARKS UPON BATTERIES. 25 

of the belts and ropes. These inevitable causes of the 
slackening, which absorb a part of the motive power at 
the cost of the useful work desired, are called passive re- 
sistances. Every one knows that these resistances should 
be diminished as much as possible, and that they cannot 
be totally suppressed. 

Attention should be called to the fact that in many 
cases no useful work is done, and that there then remain 
only passive resistances. If the miller takes away his 
millstones and still permits the mill to turn, it is evident 
that there remain only those passive resistances (friction 
and others) which are produced by the machinery remain- 
ing in motion. If all the machines of a large factory 
be disconnected from the motion-giving steam-engine 
and the engine continues to turn, there will only be 
present the motive force furnished by the engine itself 
and the passive resistances existing in the engine, in the 
shafts, and in the different agents of the transference of 
the movement which are still in motion. If now the 
steam-engine runs entirely alone, not being connected 
with any shaft or any piece of machinery outside of it- 
self, we have not only the example of a system in which 
there are force and passive resistances, but also that par- 
ticular instance where these passive resistances are inhe- 
rent to the force-giving machine and inseparable from the 
production of that force. 

In a circuit through which an electric current flows, 
the same terms are to be found : first, a force residing in 
the battery and which is called electro-motive force ; next, 
the work ; and finally the passive resistances. The work 
may be found in the movement of the clapper-spring of 
an electric bell ; it may be in the movement of a tele- 
graph instrument placed at a great distance from the 



26 SINGLE-LIQUID BATTEEIES. 

battery ; it may be in the movement of an electro-motor 
or an eleetro-magnetic machine which lifts a weight ; it 
may be in a chemical decomposition produced by the 
passage of a current in the production of heat and con- 
sequently of light in a voltaic, arc, etc. etc. 

Passive resistances are the results of the circulation of 
the current in the different parts of the circuit. We 
have explained how their existence may be ascertained, 
and we have designated them by this one word resistance. 

If the current produces no real work — that is, if the 
circuit is composed solely of conductors without the 
interposition of. any apparatus which puts the current 
to any use — the resistance is entirely passive. These con- 
siderations explain and justify the use of the word resist- 
ance applied to that property of reducing the intensity 
of the electric current which the conductors possess, and 
which we have demonstrated in the preceding chapter. 

ELECTEO-MOTIYE FOKCE. 

The cause which produces the electric current we 
have called electro-motive force. Before going farther we 
will show several experiments, which will render the 
ideas upon this force more precise. 

Let us take a battery cell (Fig. 3— zinc, copper, and 
water acidulated with sulphuric acid) and cause the cur- 
rent which it produces to act upon a galvanometer, and 
we will see that the needle is deflected, for instance, 
towards the right. If we change the communications 
of the battery with the galvanometer, the direction of 
the needle's deflection will be altered, which shows that 
the direction of the current in the galvanometer has been 
changed. 



GENERAL REMARKS UPON BATTERIES. 



27 



But let us consider the first conditions : the needle is 
deflected towards the right. 

Let us now take a second battery cell, differing in 
no way from the first, and insert it in the circuit. If 
the negative pole of the second be attached to the posi- 
tive pole of the first, the two currents flow in the same 
direction and join each other ; the intensity of the result- 
ing current is increased, and consequently the deflection 




Fig. 8. 



of the needle is greater. In these conditions the two 
battery cells are joined in intensity (Fig. 8) ; they form 
a battery of two cells. A battery of any number of cells, 
could thus be formed as we have stated above, but that 
is not the point upon which we wish to insist ; we only 
desire to recall the expression, battery cells joined in 
intensity, and to determine its exact meaning. 

Suppose now that the second cell be inserted in the 
circuit of the first ; by uniting the positive pole to the 



28 



SINGLE-LIQUID BATTERIES. 



positive pole, and the negative to the negative, in such 
a manner as to have two poles of the same name ending 
at the galvanometer (Fig. 9), the needle will remain 
stationary. This is not to be wondered at, if it be re- 
membered that the two cells tend to produce equal cur- 
rents in opposite directions. It is quite natural that 
these currents balance each other, and that there is no 
movement either in one direction or the other. It is 




Fig. 9. 



said in this case that the two battery cells are opposed to 
each other, or are joined in opposition. 

We have assumed, in the preceding, that the opposed 
cells were of equal dimensions. Each one acting alone 
would produce the same deflection of the needle, one to- 
wards the right and the other towards the left ; both acting 
simultaneously in opposite directions cause no deflection 
whatever : which is quite natural and easily understood. 

Let us now vary the experiment, and place in the 



GENERAL REMARKS UPON BATTERIES. 



29 



same circuit (Fig. 10) a small voltaic cell in opposition to 
a larger one of the same nature ; the needle will remain 
stationary, thus showing that there is no current. This 
result will appear very strange to the uninitiated reader, 
and deserves to be dwelt upon. If they are made to act 
separately, they cause the needle to deflect, one towards 
the right, the other towards the left. The current fur- 
nished by the larger one is more intense than the current 




Fig. 10. 



produced by the smaller one, as the deflections of the 
needle show. But if these two cells be opposed to each 
other, the effect of one is counterbalanced by the effect 
of the other, and no current flows through the circuit. 
The conclusion of this capital experiment is that the 
electromotive force of lattery cells does not depend ujpon 
their dimensions. 

The above experiment may be slightly modified. When 
cells of equal dimensions are opposed to each other, there 



30 



SINGLE-LIQUID BATTEKIES. 



is no deflection of the galvanometric needle. You may 
lift up the zinc or the copper of one of the cells, or even 
the zinc and copper together of one of the cells ; you 
may, in a word, increase or diminish the immersed part 
of the electrodes of one of the cells, and still there will 
be no deflection of the needle, and the electro-motive 
forces remain equal. 

To elucidate still further this subject, we will present 
a few more experiments. 




Fig. 11. 



Place two cells in opposition to each other, the one 
similar to those of which we have spoken (zinc, copper, 
and dilute sulphuric acid), and the other differing but 
slightly in appearance (iron, copper, and dilute sulphuric 
acid). The difference is the substitution in the second 
of iron for zinc. A first trial will show that the copper 
is the positive pole in the second cell as in the first ; that 
is, the current flows from the copper to the iron in the 



GENERAL REMARKS UPON BATTERIES. 31 

second, as it does from the copper to the zinc in the first. 
Place them now in the same circuit, in opposition to 
each other — that is, join the two zinc poles and connect 
the other two with the wires of a galvanometer (Fig. 11) ; 
the needle will be seen to deflect in the same direction 
as if the voltaic cell were acting alone, although the 
deflection is less. We have a right to conclude from 
this that the first cell has a greater electro-motive force 
than the second, and that the substitution of iron for 
zinc in YoltiCs battery would be detrimental. 

In this experiment we have supposed the two cells to 
he of equal dimensions, and that the electrode of iron 
was the same size as that of zinc. We can now modify 
these dimensions. Let us suppose, for instance, that a 
very small voltaic cell be placed in opposition to a very 
large cell (iron, copper, and acid). 

The direction of the deflection will be the same as in 
the preceding experiment ; that is, the electro-motive 
force of the smaller cell is greater than that of the larger 
one. This new experiment proves again, and more clear- 
ly than ever, that the electro-motive force of battery cells 
does not depend upon their dimensions, but upon the ma- 
terials used in their composition. 



MEASUREMENT OF ELECTRO-MOTIVE 
FORCES. 

It has been seen how, by means of an ordinary galva- 
nometer, the electro-motive forces of different batteries 
may be compared. The method that we have used is 
called met /tod of opposition, because it consists in oppos- 
ing equal or unequal forces to each other. 



32 SIKGLE-LIQTTID BATTERIES. 

It can be easily understood how the electro-motive 
forces of different cells may thus be measured and tables 
of these forces made out. 

Let us take two batteries, A and B, of unequal electro- 
motive forces. A first experiment will show us, for in- 
stance, that A is stronger than B. By opposing A to 2B 
we find that 2B is stronger than A. Let us now oppose 
2 A to 3B, and if there is no deflection of the galvano- 
metric needle we may conclude that twice the electro- 
motive force of A is equal to three times that of B, or 
that A = f B, or, finally, that A = l^B. 

It is seen that this method is general ; it may be varied 
advantageously in different ways. We will not insist 
upon it any longer, as we only wished to show the possi- 
bilities of these measurements and not the way to obtain 
them. 

IOTEBNAL BESISTANCE OF THE BATTEBY. 

It has been seen from the foregoing that the conduc- 
tors outside of the battery offer a certain resistance to 
the electric movement, or, in other words, a resistance to 
the passage of the current. 

We will now show by several simple experiments that 
the battery itself offers a resistance to the current it pro- 
duces. 

The elementary battery (Fig. 3) is made to act upon a 
galvanometer. Observe the deflection. Lift up gradually 
one of the electrodes, and as the immersed surface be- 
comes less the deflection diminishes. 

The result shows a decrease in the intensity of the cur- 
rent. As our former experiments have shown, however, 
that the electro-motive force does not vary under these 



GENERAL REMARKS UPON BATTERIES. 33 

circumstances, and that the other parts of the circuit do 
not change, we are justified in saying that the resistance 
of the battery has increased. 

The result would be the same if the two electrodes 
were lifted at the same time. 

The experiment may be made by separating the two 
electrodes from eacli other, still having the same extent 
of surface immersed. It is perhaps in this manner that 
the experiment is made the most clear. In these experi- 
ments the intensity of the current is seen to change with 
the distance that separates the two electrodes in the trough 
of liquid and with the section of the trough. It may be 
concluded that batteries have an internal resistance in 
themselves, and that the resistance increases with the dis- 
tance between the electrodes in the liquid, and diminishes 
when the immersed surfaces are increased. 

If the battery be considered as a force-producing ma- 
chine, it is not to be wondered at that it at the same time 
produces force and offers a resistance to that force. This 
condition is common to all machines ; a part of the 
force they produce is absorbed by those passive resist- 
ances resulting from the action of the different parts of 
the machine. In a steam-engine, for instance, the fric- 
tion of the steam in the pipes, the friction of the piston 
in the cylinder, etc. etc., cannot be avoided. 

This resistance of the battery has to be taken into ac- 
count in nearly all cases for the explanation of phenome- 
na and for the calculation of results. 

It can be seen that of two batteries in which the elec- 
trodes are of unequal dimensions, the distance between 
them being equal in each, the one having the larger elec- 
trodes offers less resistance than the other ; and it can be 
said in general that large cells, when compared with small 



34 SINGLE-LIQUID BATTEKIES. 

ones, offer less resistance, because the increase of surface 
of the electrodes is greater than the increase of the dis- 
tance between them. 

The resistance of the batteries varies with the nature 
of the liquids in which the electrodes are immersed. It 
can be easily understood that all liquids have not the same 
specific power of resistance. The conductivity of di- 
lute sulphuric acid varies with the proportions of water 
and acid mixed, and the greatest conductivity is found in 
a mixture of 29 parts of sulphuric acid (HSO 4 ) for 71 
parts of water. It has been observed that it is this mix- 
ture which, in an apparatus for the production of hydro- 
gen, attacks the zinc the most energetically. 

These reasons would lead to the use of this mixture in 
preference to all others in Yolta's battery, and indeed in 
all others in which dilute sulphuric acid is used ; but this 
mixture, being that of about one part of acid (HS0 4 ) 
for two parts of water, is not used in the practice, as it 
would be too dangerous to handle, and as it is also rather 
costly ; therefore the mixture of ten or twelve parts of 
acid for one hundred parts of water is adopted. 

It is understood that as soon as a battery is put into 
working order and the chemical action takes place, the 
composition of the liquid changes, and consequently the 
resistance. 

¥e will return more than once to this important point. 

VARIOUS WAYS OF JOUSTING VOLTAIC 
CELLS. 

We have seen (Fig. 9) how two battery cells of the 
same kind may be placed in opposition to each other in 
such a manner as to counterbalance each other. Let us 



GENERAL REMARKS UPON BATTERIES. 



35 



now take away the galvanometer that we had placed in 
the circuit of these cells and we will still have two cells 
joined in opposition. 

Let us consider the two cells thus joined. If the gal- 
vanometer be put into communication, on one hand with 
the wire connecting the two positive poles, and on the 
other hand with the wires connecting the two negative 
poles, the passage of a very strong current w T ill be ob- 
served. The currents of the two cells, which were at first 




Fig. 12. 

opposed to each other, now flow together in the galva- 
nometer, The two battery cells are then said to he joined 
in quant iff/. + 

The metallic piece which connects the two zinc poles 
may be considered as the negative pole common to both 
cells, and the other as the positive pole common to both 
cells. 

It may be observed that the two cells ought to pro- 



36 



SINGLE-LIQUID BATTERIES. 



duce the same effects as a single one, in which the elec- 
trodes would have a double surface, while the distance 
between them would remain the same. 

The internal resistance offered by the two cells is only 
half of that offered by each one alone, while the electro- 
motive force remains the same. This may 
be demonstrated by placing a third cell of 
the same size and kind in opposition to these 
two cells joined in quantity, Fig. 12. The 
galvanometric needle does not deflect, which 
shows once more that the electro-motive force 
does not depend upon the size of the elec 
trodes, but solely upon their nature. 

There is, finally, a third way of joining 
these two cells ; namely, joining them in in- 
tensity, of which we have already spoken. 
This manner consists in uniting the positive 
pole of one of the cells to the negative pole 
of the other. In this arrangement the electro- 
motive force of the two taken together is 
double that of each separately; the resist- 
ance is also double. 

These different ways of joining battery 
cells may be ajDplied to any number of cells. 
Let us take, for instance, six cells and join 
them in intensity, Fig. 13. If the electro- 
motive force of one cell be symbolized by E, and its 
resistance by E, it is evident that a battery of six cells 
joined in intensity will have an electro-motive force equal 
to 6E, and a resistance equal to 6K. 
If all be joined in quantity, Fig. 14, the electro-motive 

force of the battery will be E, and the resistance -pr • 



Fig. 13. 



GENERAL REMARKS UPON BATTERIES. 



37 



If they be joined by twos in intensity and by threes in 
quantity, Fig. 15, the electro-motive force will be 2E, 
and the resistance f R. 




They may, finally, be joined by threes in intensity and 
by twos in quantity, Fig. 16 ; the electro-motive force will 
be 3E, and the resistance j-TL 





Fig. 15. 



Fig. 16. 



38 SINGLE-LIQUID BATTEKIES. 

As long as, in this last combination, there is no con- 
nection with any outside circuit, the three cells on the 
right are in opposition to the three on the left. 

It is not necessary for us to insist longer upon this 
subject, or to make calculations which are indeed very 
simple, to make the reader understand that, with a suf- 
ficient number of cells, a battery may be obtained whose 
electro-motive force will be as great, and whose resistance 
will be as little, as can be desired. 

In most applications, and notably in the electric tele- 
graph, there is only the need of increasing the electro- 
motive force, and very little attention is paid to the re- 
sistance. 

In certain instances, however, too great a resistance 
would be very detrimental ; it is then that the cells may 
be joined in quantity. In practice, large cells having a 
very slight internal resistance are employed. 

VOLTAMETER. 

Before proceeding with the study of batteries, it would 
be well to stop and examine some of the effects they pro- 
duce. Of all the chemical actions that can be brought 
about by means of electric currents, the decomposition of 
water is the most striking. It is done in an apparatus 
called voltameter, and is represented in Fig. 17. 

Two wires or plates of platinum are placed parallel to 
each other in a jar containing dilute sulphuric acid. 
These two electrodes pass through the bottom of the 
jar and are attached to binding screws, or terminals, to 
which the wires of a battery are fastened. 

If a sufficiently energetic current be made to pass in 
this apparatus, bubbles of gas will be seen to free them- 



GENERAL REMARKS UPON BATTERIES. 39 

selves from the surface of the electrodes; If these gases 
be collected in proper gas-measuring jars, oxygen will be 
found in one and hydrogen in the other. If they be 
collected together in a single jar, they will be found to 
be sensibly in those proportions whose combination pro- 
duces water. We say sensibly, for the proportion is 
nearly always altered by complicated disturbing actions, 
upon which we cannot here enlarge. 




Fig. 17. 

The electrode by which the current enters the appa- 
ratus is called positive electrode of the voltameter ; it is 
that which is connected with the positive pole, or, in 
other words, with the negative electrode of the battery 
which furnishes the current. 

The negative electrode of the voltameter is connected 
with the negative pole, or positive electrode or generat- 
ing electrode of the battery. 

The oxygen which appears upon the positive electrode 
of the voltameter is termed electro-negative y the hydrogen 
which is seen at the surface of the negative electrode of 
the voltameter is termed electro-positive. 

These denominations may embarrass beginners. In 
order to employ them correctly the key is needed, and 



40 SINGLE-LIQUID BATTERIES. 

this may be found in the old theoretical ideas upon the 
two electric fluids, the one positive and the other nega- 
tive. There is, at each point in a circuit through which 
a current flows, a reuniting of positive and negative elec- 
tricity ; the negative electricity of the oxygen is attracted 
by the positive electricity of the positive electrode, and 
so on. This circuit is considered as a chain, in which 
one end of each link is positive and the other nega- 
tive. 

The theoretical ideas have changed, but the expressions 
have remained, the alteration of which would only involve 
difficulties, because they are not in disagreement with the 
new scientific views. We will not enter into the details 
of this demonstration, but will return to the exact appli- 
cation of these terms, in order to spare the reader the 
annoyance of certain errors to which he may be exposed. 

In general, every liquid decomposed by the passage of 
an electric current is called an electrolyte, and it is said to 
be electrolyzed as long as the electric action continues. 
Faraday has established, by numerous experiments, the 
laws of definite electrolysis. We cannot enlarge upon 
this delicate subject. We will only say that, if two or 
three cells joined in intensity produce a current used to 
electrolyze water, for instance, for each chemical equiv- 
alent of hydrogen set free in the voltameter there will 
be an equivalent of zinc dissolved in each cell of the 
battery. The law of Faraday may be said to be the 
equivalence of chemical work in all parts of the cir- 
cuit. 

If the experiment be made with six cells, instead of 
with three as indicated above, the quantity of hydrogen 
set free in one minute is much greater. An idea of the 
quantity of electricity is thus obtained, and it can be un- 



GENERAL REMARKS UPON BATTERIES. 41 

derstood how the instrument called voltameter permits 
one to measure this quantity. It owes its name to Fara- 
day, who was perfectly justified in so calling it, as it is 
in truth an instrument of measurement. The same can- 
not be said of the galvanometer, which it would be better 
to call galvanoseope ; for in general it does not measure 
the intensity of the current which passes through it, and 
it is only by means of complicated contrivances that any 
measurements can be obtained from its indications. 

Unhappily the voltameter is not convenient for use. In 
many cases it gives no indications, and in others produces 
false results, on account of the resistance which it intro- 
duces into the circuit. It presents other causes of error, 
as will be seen in the following pages. 

SECONDARY CURRENTS. 

POLARIZED ELECTRODES. 

If the voltameter be submitted for a short time to the 
action of a current, its electrodes acquire remarkable 
properties, which may be recognized in the following 
manner : 

Detach the wires connecting the voltameter to the bat- 
tery, and then connect the voltameter with a galvanome- 
ter ; the galvanometric needle will be seen to deflect, thus 
making manifest the passage of a current furnished by 
the voltameter. The direction of the current is such as 
to show that that which was the negative electrode of the 
voltameter in the experiment with the battery has be- 
come, in the experiment with the galvanometer, the posi- 
tive pole of this new source of electricity. In other 
words, the current flows in one direction in the first case, 
and in the opposite direction in the second case. It may 



42 SINGLE-LIQUID BATTEEIES. 

be said that the voltameter lias been charged with a part 
of the current of the battery, and that the voltameter re- 
turns this current in the contrary direction. 

It has been said that the electrodes are polarized, which 
is indeed true ; for they have been rendered capable of 
acting as poles. This is the origin of the expression 
'polarization of the electrodes which we have already used, 
and which we will frequently have occasion to employ. 

The current furnished by the polarized electrodes of 
the voltameter in the conditions indicated above is called 
a secondary current ; the voltameter acts as a secondary 
battery. The secondary current thus obtained lasts but a 
short time, and its intensity is seen to diminish rapidly 
from the moment it begins to circulate in the galvanome- 
ter and is soon reduced to nothing. 

We will again have occasion to speak of secondary bat- 
teries, of which we have just given an example, and which 
have lately undergone vast improvements. . 

POLARIZATION OF A VOLTAIC CELL. 

If the current furnished by a voltaic cell (one of Wol- 
laston's, for instance) with well-amalgamated zinc be 
examined by means of a galvanometer, the intensity is 
seen to diminish from the moment the circuit is 
closed. 

This diminution is very rapid if the circuit has but 
very little resistance ; it is, on the other hand, very slow 
if the circuit offers great resistance, as in a long line of 
telegraph. 

If, after having allowed the current to flow for five 
minutes, for instance, the circuit be left open for five 
minutes, it will be seen when again closed that the cur- 



GENERAL REMARKS UPON BATTERIES. 43 

rent lias nearly assumed its first intensity. It can be said 
then, the battery when not at work regains its initial 
power. 

It may be understood from these observations how it 
lias been possible to use the sand-battery for a number of 
years in the telegraph service ; the telegraph lines offer- 
ing indeed great resistances, but only needing intermit- 
tent currents. 

By closely examining that which takes place while the 
circuit is closed, different circumstances of the phenome- 
non will be seen, which will throw a great deal of light 
upon the causes to which it must be attributed. 

At first bubbles of hydrogen are seen to form them- 
selves upon the copper electrode, as we have already 
stated ; this will lead to the belief that imperceptible 
bubbles form themselves upon the entire surface in such 
a way as to interpose, more or less completely, between 
the electrode and the liquid, a gaseous layer. Thus appar- 
ently the principal cause of the diminution in the intensity 
of the current should be sought at the surface of the cop- 
per electrode. 

Several simple experiments will confirm this. 

If, after a marked diminution in the deflection of the 
galvanometric needle, the electrodes be shaken without 
lifting them out of the liquid, the current is seen to partly 
recover the force it had lost. 

The same thing is observed if the liquid alone be 
shaken without moving the electrodes, and consequently 
without changing the extent of the immersed surface. 

The moving of the copper electrode alone will show, 
as a result, the recovery of the lost force. 

By rubbing the copper, without taking it out of the 
liquid, with a small brush, the same result is noticed. 



44 SINGLE-LIQUID B-ATTERIES. 

In these three experiments the disappearance of bubbles 
of hydrogen from the surface of the conducting electrode 
is accompanied by a renewal of the intensity of the current. 

If, on the other hand, the zinc electrode alone be agi- 
tated, no perceptible modification in the decrease of the 
current takes place. 

Henceforth there can be no doubts as to the impor- 
tance of the phenomenon which takes place at the surface 
of the copper electrode. The diminution of intensity 
that we have observed may be attributed to two causes : 
either to the increase in the internal resistance of the 
battery, or to the decrease in the electro-motive force. 
In fact, the two causes are present at the same time. 
That the resistance increases cannot be doubted, since the 
active surface of the copper electrode is diminished ; but 
a simple and direct demonstration of this does not seem 
easy to obtain. 

That the electro-motive force is diminished is ex- 
tremely easy to demonstrate. For this experiment we 
employ the method of opposition which we have already 
described, and which is as convenient for the comparison 
of electro-motive forces as are scales for the comparison 
of weights. 

The instant the electrodes are immersed in the liquid 
and the battery begins to work, it attains its maximum 
intensity. 

Let us now take two identical battery cells and close 
the circuit of one of them for five minutes, leaving the 
other inactive. At the expiration of iive minutes, place 
the one that has been working in opposition to the fresh 
one, and a galvanometer interposed in the circuit will 
show the superiority of the electro-motive force of the 
fresh cell. 



GENERAL REMARKS UPON BATTERIES. 45 

If now these two cells be made to act separately, each 
upon itself — that is, without the insertion of any resist- 
ance during; five minutes — it will be found at the end of 
that time, by placing them in opposition, that the second 
*me still has a greater electro-motive force than the first 
one. 

The experiments could be varied, and it could be ascer- 
tained, for instance, how long the decrease continues in a 
cell of a certain size and form and under well-known 
circumstances. 

It can be easily shown that the electro-motive force of 
a voltaic cell can, by constant action, be reduced one 
half. For this it is only necessary to cause two cells to 
work a considerable length of time ; when they are sup- 
posed to be exhausted as much as they can be, join them 
in intensity and place this battery of two cells in opposi- 
tion to an entirely new cell ; the galvanometer will still 
mark the superiority of the latter, and the necessary con- 
clusion is that the electro-motive force of each one of the 
two exhausted cells has been reduced to less than half of 
that of the new cell. 

It is admitted that the diminution in the electro-motive 
force of batteries is due to the production of an electro- 
motive force (upon the surface of the negative electrode) 
contrary to that of the principal current. 

This view is founded upon that which we have said of 
the electro-motive force found in a voltameter, from 
whose electrodes gases are given off. 

It may be shown by a direct experiment that the con- 
ducting electrode C of a weakened battery has acquired 
peculiar properties. It is only necessary to immerse in 
the liquid a second plate of copper, C, and to connect the 
two with a galvanometer. The passage of a current is 



46 SINGLE-LIQUID BATTEKIES. 

thus made manifest, and its direction shows that the 
copper plate C acts as the soluble electrode, or electro- 
positive, when compared with the other, C, which assumes 
the part of a conducting electrode, or electro-negative. 
This current commences to decrease from the moment it 
is established, and soon becomes imperceptible. Thus the 
electrode C, which was electro-negative in the voltaic cell 
before and during its weakening, is electro-positive in the 
test cell of two copper electrodes. Finally, if after the 
above experiment the voltaic cell be re-established, it as- 
sumes its original intensity, at least for a moment, and 
then begins to weaken again, as in the first instance. 

It is then that the conducting electrode is said to be in 
a state of polarization. 

Such is the phenomenon of the polarization of the 
negative electrode of batteries, a knowledge of which is 
so important. 

It will be seen, in the following pages of this work, 
that the less the polarization, the better the batteries. 
The most important improvements in batteries are those 
which have had in view the diminution or suppression of 
polarization. In other words, the principal aim and effort 
of inventors worthy of that name has been to depolarize 
the electrode. 

It has been established that polarization remains the 
same when the size of the cell and the intensity of the 
current are in proportion to each other. It is here neces- 
sary to define polarization : it is the difference between 
the electro-motive forces in a polarized battery aiid a 
depolarized battery. 

It can be understood indeed that the quantity of 
hydrogen given off upon the negative electrode is in 
proportion to the intensity of the current 5 and that if 



GENERAL REMARKS UPON BATTERIES. 47 

this quantity distributes itself upon the surface of an 
electrode also proportional, the thickness of the deposit 
will be the same, and consequently its intrinsic action 
will not have changed. The practical conclusion of this 
law is that polarization will be less in a battery having 
large electrodes than in a smaller one, although the total 
resistance be the same. 

POLARIZATION IN A BATTERY OF SEVERAL 
ELEMENTS. 

Thus far, each time that we have spoken of the polari- 
zation of the negative or conducting electrode of cells, 
we have implicitly supposed the cell to be alone, and 
that the current which produced the polarization was the 
current of the cell itself. In ordinary practice it is not 
thus ; several elements are generally joined in intensity, 
and the current which flows in each one is furnished by 
the entire battery. 

Let us place 10 cells, each having 10 units of resistance, 
in a circuit of 100 units (total resistance 200 units) ; it is 
clear that the current will be more intense than if 9 of 
the 10 cells were taken away ; consequently the current 
which produces the polarization in each cell will be more 
energetic than if there were only one cell. 

The result is that the weakening due to polarization is 
more marked in cells which are joined in intensity than 
when they are separate. 

In other words, when a current, passing through a cell, 
is more energetic than the current which the cell itself 
produces, the weakening of the current takes place under 
the following circumstances : 

At first hydrogen is given off upon the copper, and 



48 SIKGLE-LIQUID BATTERIES. 

produces that which we have termed polarization of the 
cell. 

But afterwards, when the greater part of the acid is 
converted into sulphate of zinc, the sulphate itself be- 
comes electrolyzed and reduced zinc deposits itself upon 
the copper. If at last this deposit covers the entire sur- 
face of the copper, it can be easily seen that the two 
electrodes will become identical, and consequently it is 
no longer a battery cell. 

We shall show instances where some of the cells of a 
battery not only cease to produce a current in the right 
direction, but actually produce a reverse current. 



CHAPTER IV. 
SULPHURIC-ACID BATTERIES. 

At tlijB point which we have now reached we are able 
to compare different batteries and to undertake their 
study. 

Up to this time we have only shown Volta's battery 
and the modifications in its arrangement. We will now 
examine batteries which are analogous, but which differ 
more and more from the first model. 

This study will show how Yolta, in spite of his imper- 
fect means, happily chose the elements which have been 
used ever since ; it will be seen how advantageous and 
how imperative the use of zinc is. 

We will first study those batteries in which the liquid 
is dilute sulphuric acid, but in which the electrodes differ 
from those in the voltaic battery. 

BATTERIES WITH CARBON ELECTRODES. 

A battery differing from Yolta's only in the substitu- 
tion of carbon electrodes for those of copper is very 
often employed ; it was invented by Mr. Walker in 1849. 

In these cells the negative electrodes are made of gas 
carbon, which forms a shell upon the heated retorts in 
the preparation of gas. This substance has a very good 
conducting power, and it is very porous. On account of 
this porosity the electrode presents a considerable surface, 
and is very slowly polarized. 



50 SINGLE-LIQUID BATTEEIES. 

We have already explained, in speaking of Wollaston's 
battery, why it was advantageous to give the largest sur- 
face possible to the conducting electrode from which 
hydrogen is given off. The method that we have given 
to show the progress of polarization in a battery cell proves 
the superiority of a battery with -carbon electrodes over 
that of Yolta of equal dimensions. 

The zinc may be placed between two plates of carbon, 
or better still in the centre of a hollow cylinder of car- 
bon, always having in view the increase of the surface to 
be polarized and the checking of the polarization. 

MANTTFACTUKE OF CAKBON ELECTRODES. 

When carbon electrodes have simple geometrical forms, 
or when they are simple plates more or less thick and 
wide, they may easily be. cut from the residue in gas- 
retorts, and that is what is generally done. 

But if they are cylindrical, and especially hollow cylin- 
ders like that shown in Fig. 18, the above process cannot 
be applied. The electrodes must be produced artificially 
in moulds, by pressing powdered carbon with proper 
cements. 

Bunsen suggests the following process to make carbon : 

A mixture of one part by weight of coal and two of 
coke is made (both having been reduced to an impalpable 
powder), which, placed in a sheet-iron mould, is heated to 
clear red until all gases have been given off. The carbon 
is then dipped in molasses and left to calcinate, protected 
from the air. 

John T. Sprague, of Birmingham, recommends the 
following'process : 

" Plates or blocks may be built up from powdered 



SULPHURIC-ACID BATTERIES. 



51 



graphite mixed up with coal-tar or strong rice-paste 
into a stiff dough, which should be dried, heated, then 
packed in powdered carbon in a closed vessel and heated 
to clear red for some time. When cool they should be 
soaked in strong syrup of sugar, or treacle, again dried 
and treated as before ; this process must be repeated 
until the carbon is perfectly dense and strong." 




Fig. 18. 

USE OF CARBON ELECTRODES. 

The chief difficulty with carbon is in making the con- 
nection. The contact between the carbon and the me- 
tallic rheophore, by which it is connected with the adjoin- 
ing cell or with the circuit, must be perfect. 

This is commonly done by fixing a clamp on it to which 
the rheojphores are attached. 



52 SINGLE-LIQUID BATTERIES. 

A better plan is to deposit copper on the upper part 
and then solder the connection to it, as this gives continu- 
ous circuit. There is one drawback, however : the acid 
is soaked by capillary action into the pores of the sub- 
stance, reaches the surface of the carbon and the inner 
surface of the copper, which it attacks, thus destroying 
the connection. It is easy to avoid this action by im- 
mersing the upper part of the carbon in melted paraffin. 
The pores of the immersed part are thus filled by the 
paraffin, which, when left to cool, becomes solid. All 
capillary action through the upper part of the carbon is 
thus prevented. 

The top of the carbon may also be immersed in melted 
zinc. But by capillarity the liquid can ascend and attack 
the zinc as it did the copper. The sulphate of zinc 
would present the same difficulties as the sulphate of cop- 
per, and it is also desirable in this case to dip the upper 
part of the carbon in paraffin. The experiment shows 
that paraffin does not affect the conductivity of the car- 
bon, and that the resistance of the battery is not increased 
by this addition. 

Lead may also be deposited upon the top of the carbon, 
but here the paraffin is indispensable, because the forma- 
tion of sulphate of lead is enough to diminish consider- 
ably the intensity by introducing in the current a matter 
almost without conductivity and nearly insoluble. 

In Switzerland the battery which we have above de- 
scribed is extensively used, especially in telegraph offices. 
The zinc should be well amalgamated before being placed 
in the centre of the carbon cylinder (Fig. 18), in order 
to diminish local actions while the battery is at rest ; 
owing to this precaution the battery may be used a long 
time without any care being bestowed upon it. 



SULPHURIC-ACID BATTERIES. 53 

"We will see farther on how this battery has been im- 
proved upon by substituting a solution of sea-salt for the 
dilute sulphuric acid. 

ZINC-IRON BATTERY. 

One of the first ideas, and the most natural, is to use 
iron on account of its cheapness. Iron may indeed be 
substituted for the copper, but a battery thus arranged is 
very inferior to that of Yolta. The substitution of iron 
for copper causes a notable diminution in the electro- 
motive force. It is important to note, however, that the 
copper may be effectively replaced by iron ; that it is still 
the zinc which is attacked ; and that the iron is preserved 
from the action of the sulphuric acid while the circuit is 
closed. 

IRON-COPPER BATTERY. 

In Yolta's battery it is the zinc which is continuously 
dissolved ; it is therefore logical to search for something 
which may replace the zinc and which at the same time 
is less costly — iron, for instance. This substitution of 
iron for zinc would be more advantageous than the sub- 
stitution of iron for copper ; but this battery (iron, cop- 
per, and sulphuric acid) is still inferior to the preceding 
one. 

OTHER COMBINATIONS. 

If the question of economy be put aside, many other 
combinations might be usefully employed ; but, as we 
have said, the use of zinc is necessary, as no other metal 
practically acceptable can be advantageously substituted. 



54 SINGLE-LIQUID BATTEBIES. 

Even aluminium is less liable to be attacked, or, as it is 
said, is less electro-positive than the zinc. Only calcium, 
sodium, potassium, and analogous metals are more electro- 
positive. It is needless to say, however, that they cannot 
be used in batteries destined for practical purposes. 

For the negative or insoluble electrode there is, on the 
other hand, great choice : lead, silver, and platinum can 
be and are often employed. The electro-motive force of 
a zinc-platinum battery is rather superior to that of Yol- 
ta's (zinc-copper), and is about equal to the zinc-carbon 
battery. 

Following is a list of metals so arranged that if any 
two be taken to form the electrodes of a dilute sulphuric- 
acid battery, the one nearest the end of the list will be 
the positive electrode, or the negative pole of the cell thus 
arranged : 

1. Silver. 4. Bismuth. 8. Tin. 

2. Copper. 5. Nickel. 9. Cadmium. 

3. Antimony. 6. Iron. 10. Zinc. 

7. Lead. 

Too great an importance must not be attached to this 
list, for the order of the metals would be different if the 
liquid were other than dilute sulphuric acid. 

SMEE'S CELL. 

Many ways have been devised for reducing the polari- 
zation of the negative electrode of the batteries which 
we have described. In 1840 Smee indicated a very inge- 
nious way, which consists in using electrodes of platinum, 
upon whose surface he deposited, by means of electricity, 
platinum as a fine black powder. These electrodes of 



SULPHURIC-ACID BATTEEIES. 



55 



platinized platinum tend to diminish considerably po- 
larization. The simple reason of this is that the bubbles 
of hydrogen free themselves much more easily than from 
the polished surface of a metal. 

For reasons of economy Smee placed the platinum 
plate between the two plates of zinc. It is in form a 
reversed Wollaston battery. 

Smee's battery is charged with a solution containing 
one part of acid to seven parts of water. Its work is 
much greater than could be expected from a single-liquid 
battery. 

Again, for economy, Smee replaced the platinized 
platinum by platinized silver. The following composition 




Fig. 19. 



had even been used, which produces a much cheaper 
cell: 

Upon a plate of copper is deposited a grainy layer of 
copper, then a layer of silver, and finally a layer of plati- 



num dust. The 



rough 



surface thus given to the silver 



facilitates the deposit of platinum, which is very difficult 
upon polished silver. 



56 SIKGLE-LIQTIID BATTERIES. 

One of Smee's batteries would give very unsatisfactory 
results if the zinc were not amalgamated ; it is a precau- 
tion that should not be neglected. 

This battery is extensively used in England and the 
United States with many modifications, one of which is 
presented by Fig. 19. 

WALKER'S PLATINIZED CARBON BATTEEY. 

We have stated above how, since 1849, Walker had 
used batteries with electrodes of carbon cut from the 
gas-retorts. In 1857 he resolved to platinize his carbons, 
and the battery thus constructed has been used by the 
South-Eastern Railway in England with great success ; 
nine thousand of these cells were in service in March, 
1875. 

These cells are contained in an earthen jar, and the 
lower extremity of the zinc is immersed in a gutta-percha 
saucer filled with mercury ; the zinc is well amalgamated, 
which reduces to its minimum the local action or losi 
chemical work ; the top part of the carbon is copper- 
plated and tinned. 

The usual size of these cells is 4 inches by 2 inches ; 
their price (with the mercury and sulphuric acid), 42 cents. 

The cost of keeping them in order is calculated at 25 
cents annually. 

This battery may be left twelve, fifteen, and sometimes 
seventeen months without needing any care whatever. 

It is a simple modification of Smee's battery, and with 
a liquid of one part of acid to eight parts of water there 
is an electro-motive force equal to that of Smee's (meas- 
urements made before any polarization). Polarization 
may reduce the electro-motive force one half. It will 



SULPHURIC-ACID BATTERIES. 



57 



be seen from the tables at the end of this work that this 
force is equal to that which is taken as the unit ; namely, 
that of Daniell's battery. 

The internal resistance of Walker's battery is about 
1 ohm, or 1 unit. It is certainly a very small resistance 
for a telegraph battery, a quality which we must point 
out. 

TYEE'S BATTERY. 

Tyer combined a modification of Smee's batteries, for 
the service of electric railroad signals, which presents 
many advantages. 




Fig. 20. 



In the bottom of the jar (Fig. 20) are placed a sufficient 
quantity of mercury and pieces of zinc ; this constitutes 
the generating electrode. 

A plate of platinized silver is held vertically in the jar 



58 SINGLE-LIQUID BATTEKIES. 

by means of a cross-piece of lead which rests on the rim 
of the jar, thus giving a good height and a certain firm- 
ness to the conducting electrode. The top of the cross- 
piece of lead is furnished with a terminal, to which is 
fastened a copper wire covered with gutta-percha ; at 
the end of this wire is a ball of zinc which is wholly 
immersed in the mercury of the adjoining cell. 

The liquid is sulphuric acid diluted with twenty times 
its volume of water. 

This battery has the advantage of consuming frag- 
ments of zinc and using them to their last particle. Those 
pieces which are wasted in the manufacture of other bat- 
teries can here be put to use. In this respect Tver's is 
the best arrangement yet produced. 

The maintenance of this battery is reduced to a 
minimum, for in a well-closed box it can remain two or 
three years without examination. Great care should be 
taken, however, in the charging and cleaning of the bat- 
tery, in order to avoid any loss of mercury. 

BARON EBJSTER'S BATTERY. 

To the Austrian general, Baron Elmer, is due the fol- 
lowing arrangement of Smee's battery. The negative 
electrode is of platinized lead ; the generating electrode 
is, as in the preceding arrangement, composed of frag- 
ments of zinc in some mercury, which keeps them well 
amalgamated. 

A very large battery of this kind was used at the 
Paris Exposition of 1867 to run electric clocks ; which 
proved that the polarization was but slightly felt, as 
electric clocks do not work well unless a very constant 
current is provided. 

The electro-motive force of this battery is only about 



SULPHURIC-ACID BATTERIES. 59 

half that of Daniell's battery, of which we will speak 
farther on, and which is generally taken as a term of 
comparison. Its maintenance is very economical, for the 
same reasons given in the description of Tyer's battery. 

BATTEEIES ANALOGOUS TO THAT OF SMEE. 

Following Smee's example, Poggendorff deposited pul- 
verized copper upon a copper electrode and thus obtained 
a battery of Yolta, or of Wollaston, notably improved, 
inasmuch as the polarization takes place less rapidly and 
with less intensity. 

Drivet, an Italian officer, carried out an analogous idea. 
He deposited upon the copper electrode of a voltaic cell 
a very thick layer (^ of an inch) of spongy copper. The 
porosity of this metal gives it some of the qualities of 
carbon electrodes. The analogy with Smee's battery is 
more apparent than real, for the very thin layer of pul- 
verized platinum does not present the increase of surface 
which is the advantage in the use of carbon electrodes. 

We have ourselves tried a battery in which the nega- 
tive electrode is a plate of lead, upon whose surface a 
layer of spongy lead -£$ of an inch thick is deposited. 

EEMAEKS UPON POLAEIZATION IN THE 
PEECEDINO BATTEEIES. 

We have seen in all batteries described thus far that 
polarization was the result of the freeing of gaseous bub- 
bles of hydrogen from the negative electrode. 

We have indicated several means, devised by different 
physicists, to diminish this effect, which is done either 
by increasing the surface of the electrode to be polarized 
(Wollaston's battery, carbon-electrode battery, and Dri- 



60 SINGLE-LIQUID BATTERIES. 

vet's battery) or by modifying this surface in such a way 
as to facilitate the freeing of the gas (Smee's and similar 
batteries). The action of a battery is already vastly im- 
proved by giving a rough surface to the polarized elec- 
trode, instead of leaving it polished. 

We have also shown how the air acts favorably upon 
batteries, either by diminishing polarization while they 
are at work or by producing depolarization when the 
current has ceased to flow. Depolarization would un- 
doubtedly take place in the absence of the oxygen of the 
air, by the freeing of gas or by its dissolution in the 
liquid ; but the oxyen renders depolarization much more 
rapid, especially in the case of carbon electrodes, by com- 
bining with the hydrogen to form water. 

We will indicate, as we proceed, much more effectual 
means for diminishing or suppressing polarization, which 
consist in the use of substances placed near the negative 
or conducting electrode, and by which the hydrogen is 
chemically absorbed. These are the only contrivances 
by which constant batteries can be produced ;' that is, 
batteries whose electro-motive force is constant. 

We will describe in detail these constant batteries, 
which present a satisfactory solution of the problem of 
obtaining a continuous and regular electric current. 
They have taken the place of simple and inconstant 
batteries in all applications, and their study will be the 
crowning of the present work. 

But in order to proceed from the simple to the com- 
plex we ought to describe several other inconstant bat- 
teries, only a few of which have any practical interest. 
Their study is, however, necessary in order to under- 
stand the many varieties already tried and those which 
might be tried. 



CHAPTER V. 
ACID BATTERIES ANALOGOUS TO THAT OF VOLTA. 

Thus far we have considered a series of batteries dif- 
fering very little from each other, all being composed of 
two different electrodes immersed in a single liquid, di- 
lute sulphuric acid. 

It is easily understood that by replacing the sulphuric 
acid by other acids, new batteries analogous to the first 
ones may be obtained. . 

HYDROCHLORIC-ACID BATTERIES. 

The cheapness of hydrochloric acid caused many per- 
sons to use it ; but none of the batteries thus constructed 
obtained any continued application, because hydrochloric 
acid, being gaseous and only soluble in water, escapes into 
the surrounding air, so that after a short time it is im- 
possible to remain in the room where it is placed. 

Besides, the hydrochloric acid liberates itself rapidly 
from the water in which it is dissolved, at least a good 
part of it, the liquid becoming immediately impoverish- 
ed, and a new cause of the weakening of the current is 
added to those which we have already pointed out. 

NITRIC- ACID BATTERIES. 

Nitric-acid batteries could be very easily made, but 
they would have the same inconveniences as those with 



62 SINGLE-LIQUID BATTEEIES. 

hydrochloric acid, and would not present the same eco- 
nomical advantage. It will be seen, however, that in cer- 
tain less rudimentary combinations nitric acid is put into 
use. 

VARIOUS ACID BATTEEIES. 

All acids employed by chemists may be used in the 
composition of batteries, provided they be liquid or solu- 
ble in water and conductors of electricity. 

• Acetic acid, found in all households, may be used in 
the absence of others. It has indeed been used by Pul- 
vermacher in his electro-medical battery. The electrodes 
were zinc and copper wires wound upon small pieces of 
wood. They were connected with each other, the posi- 
tive pole of each with the negative pole of the following 
one, and dipped in diluted vinegar. Twenty years ago 
this apparatus had great success, but to-day it is replaced 
fey others more perfect. 

In all these voltaic combinations the chemical action is 
the same as in Yolta's battery. The zinc becomes oxy- 
dized at the expense of the water, and the oxide of zinc 
combines with the acid, forming a nitrate, an acetate of 
zinc, etc. The hydrogen of the water is given off upon 
the negative or conducting electrode. 

It can be seen without going any farther how many 
different batteries may be conceived by simply varying 
the nature of the electrodes and the liquid. But many of 
these combinations are far from possessing any interest, 
and our remark is only designed to call the attention of 
the reader to the number of solutions of the problem of 
constructing batteries. 



CHAPTER VI. 

BATTERIES WITHOUT ACIDS. 

In addition to the acids there are numbers of liquids 
or solutions which may be used in batteries, a few of which 
are interesting. 

SEA-SALT BATTERIES. 

On account of the facility in obtaining chloride of so- 
dium, or sea-salt, or common salt, it is often made use of 
in batteries. The battery, whose electrodes are carbon 
and zinc, is almost exclusively used in Switzerland for tele- 
graph purposes, with dilute sulphuric acid, or more fre- 
quently with salted water. 

There are several dimensions of these. The smallest 
has flat electrodes 2f inches long ; the next size has elec- 
trodes 4 inches long and 1-J inches wide. Both sizes have 
but a single piece of carbon in each cell. The first can 
work one month, the second three months, without care. 

These cells certainly cost very little, and there is scarce- 
ly any consumption of the zinc while the circuit is open, 
although the zinc is not amalgamated, which is a very 
satisfactory condition. The electrodes may be lifted out 
during the suspension of work, and this is facilitated by 
the electrodes being attached to a bar of wood. By lift- 
ing this bar the electrodes of ten cells may be raised at 
one time. 

Another model of this same battery is shown in Fig. 18. 



64 SINGLE-LIQUID BATTEEIES. 

The carbon has the form of a hollow cylinder, in the 
centre of which is a plate of zinc, not amalgamated, as 
we have already stated ; these two electrodes are fastened 
to a strip of wood which rests upon the rim of the jar 
containing salted water. The comparatively large surface 
of the carbon is a very favorable condition (for single- 
liquid batteries), as we explained when speaking of Wol- 
laston's battery. In the model employed on Swiss lines 
the carbon is 5J inches high, and has an exterior diame- 
ter of 3^ inches. These batteries can do service from 
nine to twelve months without requiring attention. 

The friend to whom we are indebted for the preceding 
information uses salt-water batteries for domestic bells. 
He employs cells which have ' a height of 14 inches. 
Some batteries of this kind have been known to work 
from six to eight years without any care whatever. There 
is one which worked ten years ; the zinc had of course 
disappeared. 

Concerning the weakening of this battery, it has been 
found that it may be exhausted by causing a constant 
current of a short circuit to pass for ten or twelve hours, 
and that it only needs two or three hours of rest to regain 
its lost energy. In other words, depolarization takes place 
very rapidly. 

The sea-salt battery is not only used for the telegraph 
and electric bells, but for electric clocks. 

DUCHEMIN'S ELECTKIC BUOY. 

Duchemin placed elements of the preceding form 
directly in the sea by attaching them to some floating 
body. The constant agitation of water caused undoubt- 
edly an almost complete depolarization. "When several 



BATTERIES WITHOUT ACIDS. 65 

cells are employed, however, they are in the same liquid ; 
there is therefore a small loss of electricity ; it cannot be 
of much consequence, because of the form of the carbon 
which surrounds the zinc. A- perfect insulation of the 
wires connecting the cells is of great importance. 

The main object of these batteries was the preserva- 
tion of sheets of iron used in the construction of vessels, 
barges, buoys, etc. etc. It appears that the hull of a 
vessel undergoes a relatively less change during naviga- 
tion than when at anchor or in port ; it is in this case 
that the use of Dnchemin's buoy is practicable. These 
buoys are used as follows : 

Seven cells about 4 inches in diameter, for instance, 
are joined in intensity. The positive pole of this battery 
is put into communication with the sheets of iron to be 
preserved ; the negative pole (that is, the zinc of the last 
cell) is in the sea, as indeed are the others. Under these 
circumstances it has been proved, by experiments made at 
Cherbourg by officers of the French navy appointed 
purposely by the Minister of Marine, that a surface of 
iron eighteen times larger than that of the zinc which 
forms the soluble electrodes of the battery may be pre- 
served from rust. 

It appears that the simple addition of a sheet of zinc 
is not sufficient to preserve the hull of an iron vessel 
from rust, but it can be done by means of one or seve- 
ral electric buoys ; that is the result, at least, of a pro- 
longed experiment on a small iron boat. 

These interesting experiments were unhappily discon- 
tinued during the war of 1870-71, and have not been re- 
sumed. 

Before leaving the subject, we will say that there is a 
possible superiority of sea-water over common salted 



66 SINGLE-LIQUID BATTEEIES. 

water ; for sea- water does not contain chloride of sodium 
alone. We have unfortunately no positive information 
upon this -point. 

The salted- water or sea-water battery, although inferior 
to many others (especially to the sal-ammoniac battery, of 
which we will speak later), may be recommended, above 
all, in places near the sea, where the expense is compara- 
tively small. 

ZmC-COPPER-SEA-WATEE BATTEKY. 

At the beginning of the present century the illustrious 
Sir Humphry Davy proposed to protect the copper hull 
of vessels by means of a sheet of zinc (or, indeed, of cast- 
iron) put into communication with the lining and im- 
mersed with it in the sea. A cell was thus constructed 
in which the zinc (or iron), by being attacked, protected 
the copper. 

The zinc had, of course, to be replaced at the end of a 
certain time ; but an extent of active zinc surface one 
hundred and fifty times larger than that of the copper 
was sufficient to protect the latter. This ingenious idea 
had to be abandoned in the practice for the following- 
reason : 

The zinc-copper cell of which we have spoken gives 
off, indeed, hydrogen upon the surface of the copper ; 
but at the same time it decomposes certain salts con- 
tained in sea-water, and the bases (earthy oxides — magne- 
sia and lime) deposit themselves upon the copper. To 
this crust sea-grasses and shell-fish attach themselves and 
slacken to a great extent the speed of the vessel. 

In the absence of the zinc the copper is slightly at- 
tacked by the sea- water, but the surface remains apparent- 



BATTEEIES WITHOUT ACIDS. 67 

ly clean. In the long-run the copper is used up ; but of 
two evils one must choose the less, and prefer to lose a 
little more on the resale of old linings than to increase 
the duration of voyages. 



ZINC-IEON-SEA-WATEE BATTERY. 

Within the last twenty or thirty years copper-lined 
vessels have gradually been abandoned and a great num- 
ber of iron ships have been constructed. Davy's idea is 
in this instance applicable. We do not know if many ex- 
periments have been made or not ; but the result of one 
experiment upon a French frigate showed that sheets of 
metal one metre square lost the following weights after 
remaining in sea-water one month : 

Grammes. Grammes. 

Steel 28.10 Zinc 5.60 

Iron 27.30 Galvanized iron 1.80 

Copper 3.80 Tin 1.50 

Lead only traces. 

These figures go to prove that iron is of all metals the 
most attacked by sea-water, and is therefore badly chosen, 
as far as preservation is concerned, for the construction 
of ships, buoys, etc. 

From a theoretical point of view there would be a 
great advantage in coppering or tinning iron. If the 
iron were thoroughly covered with a thin layer of cop- 
per or tin it would no longer be in contact with the water, 
and would consequently not be attacked. But a small 
accident, such as the scraping of the ship on a sand-bar, 
for instance, might be enough to chip off a little piece of 



68 SINGLE-LIQUID BATTEKIES. 

copper or tin, when the exposed iron would immediately 
be attacked. 

Thus would be established an iron-copper or iron-tin 
cell which would excite the action of the sea-water 
upon the iron. It might indeed go so far as to make a 
hole in the iron. It will be seen that the ce]l thus form- 
ed would possess peculiar conditions of activity, as the 
negative electrode is enormous when compared with the 
soluble electrode ; and besides, the constant agitation of 
the water would tend to suppress all polarization. 

In the experiments above referred to the surface of the 
sheets of metal were, of course, well cleaned before each 
experiment. 

There is no doubt as to the zinc being the electro- 
positive element of the zinc-sea-water-iron battery, and 
consequently that the iron is electro-chemically protected 
by the zinc. 

It is possible that the feeble electro-motive force of this 
cell may be insufficient for a thorough protection. There 
may also be some accessory action which might make the 
action of the cell worse than simply ineffectual, as in the 
case of the copper linings. 

This is, we think, a desirable question to elucidate. 

ACCIDENTAL REVERSING OF THE 
CURRENT. 

We have already shown how a voltaic cell may be 
rendered ineffective by electrolysis of the salt of zinc and 
the deposit of zinc upon the conducting electrode. 

"We have said that in certain cases the current could be 
reversed ; this phenomenon was observed under the fol- 
lowing circumstances : 



BATTEKIES WITHOUT ACIDS. 69 

Certain zinc-salt-water-carbon batteries that had been 
working two years were, by accident, short-circuited ; 
polarization was brought to its maximum, since there 
was no resistance in the external circuit, and consequently 
the intensity was the greatest it could be. Soon after 
the battery could supply almost no current whatever; 
and by close examination it was found that in one out of 
every four or five cells the poles were reversed ; that is, 
the zinc had become the positive pole, and the carbon the 
negative pole. There was present a polarization similar 
to that which would have taken place in a voltameter, or 
in a secondary battery placed in the circuit. This second- 
ary current neutralized, in a great measure, that of the 
other cells of the battery. 

In this singular instance the polarization of certain 
elements had become stronger than the element itself. 

It is easily understood that, if there had only been one 
cell in the circuit, this reversing of the poles would never 
have taken place ; for the cm-rent resulting from polari- 
zation is necessarily inferior in tension or electro-motive 
force to the polarizing current. 

One more remark before leaving this experiment. If 
the battery cells joined in intensity were and would re- 
main identical, the above phenomenon would not take 
place. 

If twenty cells were joined in intensity and in short 
circuit (that is, without any exterior resistance), the in- 
tensity is exactly the same as if there were but one cell 
in short circuit ; for in the first instance the electro-motive 
force is twenty times greater and the resistance of the 
circuit twenty times less than in the second instance, 
which establishes an exact compensation. 

If there be only one cell in the circuit, it cannot but 



70 SINGLE-LIQUID BATTEEIES. 

weaken, and no reversing of the poles can take place. 
Therefore in a battery whose cells are identical there can 
be no reversing. For the occurrence of this phenomenon 
the cells must necessarily be dissimilar, which is nearly 
always the case. Some are polarized from the beginning 
much more rapidly than others ; from that time they are 
no longer identical cells, and the poles of the weaker 
ones, which are the most polarized, may be reversed. 

If some of these cells should accidentally be closed 
while the others are open, they become rapidly polarized ; 
the cause of this may be the formation of climbing salts 
or other causes. This remark shows the advantage of 
the careful cleaning of batteries, in order that they may 
work regularly and for a long time. 

We will return to this subject when speaking of the 
sulphate-of -mercury battery. 

CHEMICAL ACTION IN SEA-SALT BATTEEIES. 

No one, as far as we know T , has analyzed the products 
formed in this battery ; it must be a very complex com- 
position, a mixture of chloride of sodium and oxide of 
zinc, or of soda and zinc chloride. There can only be 
conjectures upon this subject, as no analysis has been 
made. The only known fact is that hydrogen frees 
itself from the carbon. 

These analyses are probably very difficult, and the com- 
binations formed in batteries are in general very compli- 
cated ; the slowness of the actions favors the production 
of bodies more complicated than those of which mineral 
chemistry generally treats. 

Batteries may some day challenge the particular atten- 
tion of chemists, who will find, without doubt, that they 



BATTEEIES WITHOUT ACIDS. 71 

are as good as retorts and other apparatus used in labora- 
tories -for the formation of composed bodies, of which a 
considerable number have not jet been studied. We are 
sure that chemistry will lose nothing, and it is certain 
that the science of electricity will be greatly benefited 
by this study. 

The difficulty of the chemical problem presented by 
the sea-salt battery, and indeed by nearly all batteries, is 
increased by the fact that the nature of the compositions 
formed is different when the current is closed, and when 
it is open. It is certain that if there were a change in 
electric conditions, the action of affinities would also 
change. 

Our attention will again be called to this subject, when 
we will give certain reasons supporting the above sugges- 
tion. 

MARINE BATTEEIES. 

An old experiment shows that if a plate of zinc and a 
plate of copper be immersed in the sea at a considerable 
distance from each other and attached to a single con- 
ducting wire, there will be produced in this wire a cur- 
rent of considerable intensity. Whichever way it may 
be looked at, the internal resistance of this battery is very 
feeble ; either by considering the sea as the jar contain- 
ing the liquid and the two electrodes ; or, adopting recent 
views, by admitting that the electricity is lost in the 
earth (the common reservoir) at those two points where 
the line touches it. This combination is not susceptible 
of practical application, as it only furnishes dne cell and 
not a multiple battery ; but from a theoretical point of 
view it deserves notice. 



72 SINGLE-LIQUID BATTERIES. 



SAL-AMMONIAC BATTEKIES. 

By substituting a solution of chloride of ammonium or 
sal ammoniac for the liquids previously mentioned, a new 
series of batteries, analogous to those already enumer- 
ated, may be realized. We will call the reader's atten- 
tion to but two of them, which possess particular interest. 

BAGRATIOJST BATTEEY. 

The electrodes of this battery are- the zinc and the 
copper ; they are immersed in a jar filled with earth 
sprinkled with sal ammoniac. " It produces a wonder- 
fully constant current which is the result either of the 
reduction of the hydrogen upon the copper by the com- 
position formed there by the sal ammoniac, or of the 
absorption of the hydrogen by the earth itself, which 
indeed acts as a diaphragm. It is best not to put the 
two plates of the cell too near to each other, and to im- 
merse the plate of copper, before putting it in the earth, 
in a solution of sal ammoniac, leaving it to dry until a 
greenish layer is formed upon its surface." * 

In spite of these precautions, this battery has been put 
aside ; but it is possible that it may again be taken up. 

CARBON-ELECTRODE BATTERY. 

This battery differs from the preceding one in the 
substitution of carbon for copper. We have already 
explained the advantages of carbon. 

To give to these batteries their maximun force, and to 

* De La Rive, Traite d'Electricite. 



BATTERIES WITHOUT ACIDS. 73 

render polarization as slow as possible, they are arranged 
as follows : 

The carbon electrode is placed in a porous porcelain 
jar, which is then filled up with small pieces of carbon ; 
a considerable extent of surface is thus given to the nega- 
tive electrode. This porous jar is then placed in a glass 
or stoneware jar which contains the solution of sal am- 
moniac. The zinc is immersed in the liquid ; it has the 
form of a hollow cylinder, and a thickness of ^V of an 
inch is sufficient, as there is but little waste. 

This battery presents an important advantage, only 
found thus far in the Bagration battery and in the sea- 
salt battery. 

All batteries, indeed, in which the positive or soluble 
electrode is zinc in sal ammoniac have the same advan- 
tages. 

As long as the circuit is open there is no chemical 
work going on ; the action of the sal ammoniac upon the 
zinc does not commence until the circuit is closed, and 
ceases immediately upon the reopening of the circuit. 
In order to make this important point perfectly clear, 
the following experiment must be made : Place an ordi- 
nary piece of zinc in a solution of sal ammoniac and leave 
it there for some time, several weeks for instance, when 
it will be seen that the zinc is not attacked in the slightest 
degree. If now a fragment of metal, iron, or copper, el- 
even a piece of carbon, be added in the jar, it is soon seen 
that the zinc is attacked and a white salt is formed. 

It is thus seen that for the attack of sal ammoniac 
upon the zinc the formation of a cell is necessary ; if the 
zinc does not touch the metal added, no attack takes 
place. 

We will not insist upon the many consequences of this 



74 SINGLE-LIQUID BATTEEIES. 

simple experiment, but the plain result is, that, in bat- 
teries formed with zinc immersed in a solution of sal 
ammoniac, there is no chemical action except when the 
battery is doing nseful work. 

From a practical point of view this advantage of sal- 
ammoniac batteries is capital, for in most applications 
batteries only work at intervals. In the principal tele- 
graph offices, where the greatest number of telegrams 
are sent and received, only intermittent currents are 
used, but in such quantities that an almost constant 
demand for electric current is imposed upon the battery ; 
but in branch offices there are generally long intervals 
between telegrams, and there is most frequently no service 
at all during the night. 

In the application of domestic bells, the battery should 
always be ready for work night and day ; the current is 
consequently used, on an average, but a few minutes in the 
twenty-four hours. In applications of this kind it is seen 
that the period during which the batteries remain in- 
active is a hundred times, nay, two hundred times, longer 
than that during which they work, and that the economy 
should therefore be made during the time in which no, 
current is required. 

We will add that, such as it is, it could be very well 
used for electric bells, and could, if necessary, serve in 
a branch telegraph office. The battery in question has 
indeed but one fault : it becomes polarized when fur- 
nishing a current. However, for such an intermittent ser- 
vice this inconvenience disappears; for during its short 
period of work, polarization is barely perceptible, and it 
has sufficient time to disappear completely during the 
long intervals of rest. To M. Leclanche is due the dis- 
covery of the advantages presented by the sal-ammoniac, 



BATTEEIES WITHOUT ACIDS. ■ 75 

battery. He first established the fact that a battery 
could be produced in which the waste did not exceed, in 
proportion, the electricity supplied. 

Another advantage of this battery is that if, at a cer- 
tain time, it is seen to weaken and there be no sal ammo- 
niac at hand, it can be charged for the time being with 
common salt. But this means should only be resorted to 
in an emergency, as the current obtained with common 
salt is less intense than that furnished by sal ammoniac. 

ACTION OF AIE UPON THE PRECEDING 
BATTERY. 

From various experiments made with carbon-electrode 
and sal-ammoniac batteries the following conclusions 
may be drawn : 

1. The surface of the carbon should be as large as pos- 
sible compared to that of the zinc ; and by increasing the 
mass of carbon according to a given quantity of zinc, 
polarization may be suppressed. 

2. A part of the carbon should be exposed to the air; 
for it has been proved that when the carbon is totally 
immersed the intensity is diminished, but recovers as 
soon as some of the liquid has been taken out. This is 
what a French physicist calls letting the carbon breathe. 
The use of porous jars which overreach the top of the 
glass jar is very important. 

3. Preference should be given to gas-retort carbon, on 
account of its porosity, and, as we said in speaking of the 
chemical action in Volta's battery, it must be used in 
fragments large enough to permit the access of air. The 
powdered cake, formerly used, should be discarded. 

These conclusions will be readily admitted by the 



76 SINGLE-LIQUID BATTEEIES. 

reader, who can understand that the presence of oxygen 
in the pores of the carbon contributes to the depolariza- 
tion of the battery. It is possible that the particular fac- 
ulty of the carbon for absorbing gases in large quantities 
here plays some part, and that the properties of the gases 
thus condensed in the pores of the carbon may be dif- 
ferent from what they are under ordinary circumstances. 

CHEMICAL ACTION IN SAL-AMMONIAC 
BATTEEIES. 

A French chemist, in analyzing crystals formed in sal- 
ammoniac batteries, found this formula for them : 

3ZnCl, 4NH 3 , 4IIO. 

The gases given off from the element were found 
to be: 

•| volume of hydrogen. 

^ " nitrogen and carbonic acid. 

-i- " heavy carburetted hydrogen. 

These results only confirm that which we have said 
above of the complicated composition of bodies formed 
in batteries. 



OTHER BATTERIES. 
ZINC-IRON-WATER BATTERY. 

We have already spoken, several times, of batteries in 
which the electrodes were zinc and iron ; and we have 
seen that the zinc was always the generating electrode, 
and the iron the conducting electrode. 



OTHER BATTERIES. 77 

Every one knows that to protect iron from rust it is 
covered with zinc, and is then generally known under the 
name of galvanized iron. 

If the galvanized iron be exposed to rain or humidity, 
the uncovered parts of the iron constitute a cell with the 
zinc, and the iron is protected by the zinc. This electro- 
chemical protection increases considerably the impor- 
tance of the process of galvanizing iron. 

It must be said that the oxide of zinc produced by the 
exposure of the zinc to the air is insoluble in water, and 
forms a protecting layer which hinders further oxidation ; 
that is the principal reason for the use of zinc in out-door 
works alone or with iron. 



IKON-TIN BATTEKY. 

It is interesting to examine, from the same stand-point, 
tinned iron. Tin is liable to but very little alteration 
in water or when exposed to damp air. For many years 
it has been the practice to tin iron, by which its dura- 
bility is greatly increased. 

It is important to note that if the iron be exposed at 
any point it is promptly attacked, because in the voltaic 
cell formed with water, or simply damp air, the iron is 
the generating electrode. Under these circumstances the 
rust is seen to advance step by step, and to lift up and 
undermine the protecting layer of tin. This metal pro- 
tects only the part it covers, but it renders the iron more 
liable to rapid rust than if it were not there. 



78 SINGLE-LIQUID BATTERIES. 



ALUM BATTERY. 

Alum or potassio-aluminic sulphate (KA1 3 4S0 4 ) is 
employed in several branches of industry. 

A German physicist arranged a battery whose elec- 
trodes were ordinary zinc and carbon, and whose liquid 
was a solution of alum ; this battery undergoes polariza- 
tion, of course, but it is said to depolarize after the circuit 
has been open but a very short time. 

The chemical action must be very complicated in this 
battery. When the already complex nature of the alum 
is taken into consideration, the addition of the zinc can- 
not but lead one to believe that the composition thus pro- 
duced is extremely complicated. 

At Mulhouse they. use for electric-clock purposes a 
battery whose liquid is a mixture of sea-salt (500 grammes) 
and pulverized alum (200 grammes) dissolved in water. 
This application deserves notice, as, constant batteries arc 
generally thought to be necessary for the service of elec- 
tric clocks. 

The cells of the above battery are very large : the hol- 
low carbon cylinder has an exterior diameter of 4f inches 
and an interior diameter of 3J inches ; the plate of zinc 
is 2f inches wide, and these two electrodes are immersed 
about 10 inches in the liquid. There are twenty clocks 
distributed in two distinct circuits ; there are two clos- 
ings of the circuit a minute, each lasting one second. 
There are sixteen cells, of which two are charged every 
week in order to always keep the battery the same ; each 
cell works, therefore, four months without any attention 
whatever. 

.Another step in advance has been made in the ar- 



OTHER BATTERIES. 79 

rangement of a battery which is only renewed once in 
every two years ; it is, however, only used in the fire- 
telegraph service, which demands but little work. 

These practical examples show once more that if the 
use of single-liquid batteries is well understood, they can 
be employed in many instances. 

EEMAKKS UPON SINGLE-LIQUID BAT- 
TEEIES. . 

It might be generally said that by taking any two 
pieces of different metals, or a piece of metal and a piece 
of carbon, and immersing them in some liquid conductor 
of electricity, a battery could be made. 

The more lively the action of the liquid upon the posi- 
tive electrode (negative pole), the greater intensity the 
battery will possess; there will be no action upon the 
other electrodes, at least not during the passage of the 
current. ; that is, not while the exterior circuit is closed. 
The choice of this second electrode is, however, far from 
being a thing of indifference ; the less the electrode is 
capable of being attacked by the liquid, the greater will 
be the intensity of the battery. That is ,the reason why 
platinum and carbon should be preferred, at least with 
sulphuric acid, nitric acid, and the other liquids of which 
we have spoken. 

The electric action is the result, in reality, of the dif- 
ference of two chemical actions, one of which takes place 
while the other is prevented; one of the electrodes is 
attacked, the other is preserved from the attack of the 
liquid (at least while the circuit is closed). 

The more energetic the action upon the positive elec- 
trode and the less this action upon the negative electrode, 



80 SINGLE-LIQUID BATTERIES. 

the more developed will be the electric phenomenon. For 
instance, a zinc-acidulated water-iron battery has but little 
power ; the action of the liquid upon both electrodes is 
very lively as long as the circuit is open ; as soon as it is 
closed the action upon the iron is stopped ; but it reacts 
upon the attack of the zinc and diminishes it. If plati- 
num be substituted for iron, the zinc alone is acted upon 
and the platinum remains unattacked before the circuit 
is closed; when the circuit is closed and the current 
flows, the action upon the zinc is hardly diminished. 

Many persons have proposed compound liquids : mix- 
tures of sulphuric acid and sea-salt, mixtures of salted 
water and flower of sulphur, etc. Satisfactory results may 
possibly be obtained in this manner ; but this study has 
lost a great deal of interest on account of the invention 
of constant batteries, of which we will now speak. 



PAET II. 
TWO-LIQUID BATTERIES. 



ESTTBODUCTIOK 

We have already said that in order to successfully 
oppose polarization of electrodes, chemical substances 
capable of absorbing the hydrogen as it is given off upon 
the negative electrode must be employed. A second 
liquid is most frequently used for this purpose ; nitric 
acid is eminently suitable for this office. 

Experiment. — Let us take a zinc-sulphuric-acid-plati- 
num battery ; cause the current it furnishes to pass in a 
galvanometer. The deflection of the galvanometric 
needle is seen to decrease, and thus mark the progress of 
polarization. Let us now throw a few drops of nitric acid 
around the platinum, and the intensity of the current 
will be seen to increase immediately, thus making mani- 
fest a decrease in the polarization. It is easily understood 
that the nitric acid is decomposed by its contact with the 
hydrogen ; water and bioxide of nitrogen are formed, the 
freeing of which produces, at the contact with the air, 
nitric-tetroxide vapors, very sensible to the smell. 

In order to use nitric acid most advantageously, it 
should not be spread throughout the whole mass of the 



•82 TWO-LIQUID BATTERIES. 

liquid, but should be concentrated around the electrode 
to be polarized. To fulfil this condition porous jars have 
been adopted to separate the two liquids, one of which is 
designed to dissolve the zinc and the other to dissolve the 
hydrogen given off, or on the point of being given off, 
upon the negative electrode. 

The denomination " two-liquid battery" is badly chosen, 
because in many instances, which we will cite, solids are 
used as depolarizing agents instead of liquids ; it would 
have been more exact to say two-electrolyte battery, but 
as this appellation is not in use, we do not think best to 
adopt it. 

In most cases chemical depolarization is obtained by 
means of substances cai3able of furnishing oxygen, which, 
combining with the oxygen, prevent the~ latter from free- 
ing itself and polarizing the negative electrode. 

In the experiment that we have described above, the 
nitric acid, being decomposed, produces oxygen, and hence 
the result. Nitric acid N0 5 , being very rich in oxygen 
and easily decomposed, w T as naturally fixed upon ; it is 
one of the best batteries known. 

Other acids besides nitric acid could be used : chloric 
acid C10 5 , chromic acid Cr0 3 , permanganate acid 
Mn 2 7 are indicated ; but they are not generally used in 
this way. 

Salts (chlorate of potash, bichromate of potash, etc.) are 
generally substituted, which give off oxygen under the 
influence of the sulphuric acid. 

It may be said, in a general way, that all means of pro- 
ducing oxygen can be satisfactorily employed for the de- 
polarization of the negative electrode of a cell. 

Oxides from which oxygen is readily freed might be 
employed instead of acids ; oxygenized water would be 



IiSTEODTTCTION". 83 

excellent if the difficulty in preparing and preserving it 
did not render it practically impossible ; but the bioxide 
of manganese and the bioxide of lead may be used, as 
will be seen farther on. 

We have said how that acids rich in oxygen were not 
used alone ; they are generally in the shape of some salt 
from which they are freed by sulphuric acid, or, if need 
be, by some other. In the same manner, the combination 
of peroxides and sulphuric acid may be employed to give 
off oxygen. 

All the processes which we have just described con- 
sist in the use of oxidizing bodies or oxidizing mixtures ; 
there is one more kind to be indicated ; namely, the use 
of chlorine, which is also an oxidant in the presence of 
water, because it tends to combine with the hydrogen 
and to free the oxygen. 

All the means for producing chlorine may be used for 
depolarization. 

We have yet to speak of a chemical means of depo- 
larization very different from any that we have hitherto 
mentioned, and which according to many is the best. It 
consists in the use of salts, such as sulphate of copper, 
which decompose under the influence of the current, 
depositing their metal and checking the freeing of 
hydrogen. The result is that a metal is deposited upon 
the negative electrode instead of gaseous hydrogen ; if, 
at the start, the electrode was of cop}:)er, its surface would 
remain unchanged, and consequently there is no polariza- 
tion. 

We will examine in detail all these means of depolari- 
zation and indicate the most important applications that 
have been made, always following the same method that 
we employed in the study of single-liquid batteries. 



84 TWO-LIQUID BATTEKIES. 

The first idea upon the processes which we have just 
mentioned dates from the year 1829, and is found in a 
memoir of Becquerel. 

"It should be observed," says Becquerel, "that the 
battery carries in itself the cause of the continual diminu- 
tions in the intensity of the electric current ; for as soon 
as it begins to work, there take place decompositions and 
transportations which polarize the plates in such a man- 
ner as to produce currents contrary to the first one. The 
art consists, therefore, in dissolving these deposits, as they 
form, by means of properly placed liquids. . . . This 
is attained by means of the process that I have de- 
scribed. ... By thus diminishing the intensity of 
the secondary current, sensibly constant effects may be 
obtained." 

It is this view, so plainly expressed fifty years ago, 
that has suggested the present work and which justifies 
the classification that we have adopted. 

The first indication of a battery depolarized by means 
of a salt of the metal which constitutes the conducting 
electrode is found in the following words taken from 
Becquerel' s memoir : 

" Let us continue to use saturated solutions of metallic 
salts, which cause no decomposition of the immersed 
metal. Let us then put with the copper a saturated 
solution of nitrate of copper, and with the zinc a satu- 
rated solution of sulphate of zinc. The deflection of the 
galvanometric needle will reach 88° and then undergo 
but a slow diminution. An addition of nitric acid to the 
solution of nitrate does not modify the intensity of the 
current. The result is the same when sulphuric acid is 
added in the solution of sulphate, the zinc having been 
well cleaned. Here is then a maximum effect." 



INTRODUCTION. 85 

Finally, Becquerel speaks of depolarization obtained 
by means of nitric acid ; he experiments npon a cell con- 
taining zinc, copper, and a porous partition, the common 
liquid being a saturated solution of sulphate of zinc. He 
says : 

" According to the general rule the zinc ought to be 
more attacked than the copper, and such is the result ; 
the deflection is then 62°, and if a few drops of nitric 
acid be added in the compartment containing the copper 
plate, where the chemical action is most feeble, the gal- 
vanometric needle will mark 86° and will remain station- 
ary for some time. . . . The same quantity of acid 
put with the zinc will sensibly diminish the intensity of 
the current." A little farther on he says : "I once suc- 
ceeded in obtaining a compensation, so that the needle's 
deflections remained constant during one hour, an advan- 
tage never found in ordinary batteries." 

The only thing that escaped Becquerel' s notice is the 
part that the hydrogen plays in polarization ; he did not 
observe the nature of the chemical reactions which take 
place in those batteries now termed Daniell's battery and 
Grove's battery. He studied batteries from a purely 
physical stand-point and neglected the chemical problem. 



CHAPTEE I. 
DAWELL'S BATTERY. 

In a first series we will put all tlie batteries in which 
depolarization is effected by the use of salts. In order 
to facilitate our exposition, we ought to divide this series 
into several categories, that of sulphates, that of chlo- 
rides, etc. In fact, the two that we have just men- 
tioned are the only ones which possess any importance 
up to the present date. 

DESCEIPTIOK 

As we are not paying any attention to the chronologi- 
cal order of discoveries, we will not describe the battery 




Fig. 21. 



of Daniell under the form given to it by its inventor in 
1836 ; the form which we give is that in present use. 
Fig. 21 represents three cells joined in intensity. In 



daniell's batteey. 87 

each are seen the outside glass jar, a thin hollow cylinder 
of zinc, 2, a porcelain porous jar, and a strip of copper, c. 

The two liquids — a saturated solution of sulphate of 
copper in the porous jar and dilute sulphuric acid in the 
outside jar — are separated, but communicate with each 
other through the pores of the porcelain jar. The cop- 
per electrode is immersed in the sulphate, and the zinc in 
the acidulated water. 

The only difference between this battery and that of 
Yolta is the addition of sulphate of copper around the 
copper electrode. The zinc dissolves, oxidizing and form- 
ing sulphate of zinc. The hydrogen produced by this 
reaction, instead of being given off upon the negative 
electrode, takes the place in the sulphate of copper of an 
equivalent quantity of copper, which is deposited upon 
the electrode. This dej^osit not changing chemically the 
surface of the electrode, it is plain that there is nothing 
like polarization produced. In other words, the addition 
of sulphate of copper is sufficient to completely depolar- 
ize the negative or conducting electrode. 

Such is the simple combination due to Daniell, the 
most perfect as yet invented. 

If the action of the battery continues for some time, 
all the sulphuric acid in the outside jar will be converted 
into sulphate of zinc; the action, however, is not in the 
least checked by this, and the electro-motive force re- 
mains almost the same. The chemical action that then 
takes place consists in the substitution of zinc for the 
copper in the sulphate of copper, and the progressive 
transformation of sulphate of copper into sulphate of 
zinc. 

In general practice the battery is not charged with di- 
lute sulphuric acid ; neither is any sulphate of zinc put 



88 TWO-LIQUID BATTERIES. 

in the outside jar, but simply pure water. At first the 
action is more feeble, and the internal resistance of the 
cell much greater; but the sulphate of copper, which 
traverses the porous partition, is transformed into sulphate 
of zinc by the action of the zinc, and the pure water is 
soon found to contain a certain proportion of salt, by 
which its conductivity is increased. This first period 
lasts a longer or shorter time, according to the circum- 
stances ; but a very effectual way of shortening it consists 
in closing the circuit with a very short conductor, which 
has no resistance ; the chemical action is thus made more 
lively, and at the end of an hour or two the battery may 
be said to have reached its normal state of work. 

Electro-motive Force. — As this battery is not polarized, 
its electro-motive force ought to be invariable ; in fact, the 
two expressions are synonymous. 

The experiment shows that the electro-motive force of 
Daniell's battery is indeed very constant. In the prac- 
tice it may be taken as a unit, and others can be compared 
with it. 

The British Association has adopted a unit differing 
very little from this one, and has given to it the name of 
Yolt. The cell, in which the electro-motive force is ex- 
actly equal to the volt, differs but slightly from that of 
Daniell. It is a cell in which the copper is immersed in 
a solution of nitrate of copper, and the zinc amalgamated 
in sulphuric acid diluted with twelve times its weight of 
water. 

The electro-motive force of Daniell's cell is, we said, 
very constant, and it varies but slightly with the tempera- 
ture. 

It has been found that if it is 1000 at 18° centigrade, 
it will only reach 1015 at 100° centigrade. It changes 



baniell's battery. 89 

very little with the acidity of the liquid. If it is 1079 
with acid diluted with four times its weight of water, it 
only diminishes to 0.978 with acid diluted with twelve 
times its weight of water. The richness of a solution of 
sulphate of copper has but little influence upon it. 

M. Regnauld has given the following figures concern- 
ing a cell without sulphuric acid and charged with solu- 
tions of sulphate of zinc and sulphate of copper : 

Solution saturated with sulphate of copper 175 

The same, diluted with twice its bulk of water 175 

The same, diluted with ten times its bulk of water 174 

The same, diluted with fifty times its bulk of water 172 

These numbers are not expressed in volts, but a unit 
was taken which is equal to the electro-motive force of a 
bismuth-copper thermo-electric cell whose solderings are 
0° and 100°. 

The electro-motive force of a Daniell cell with sulphu- 
ric acid and a saturated solution of sulphate of copper is 
equal to 179 of the above units. It is therefore seen 
that the substitution of sulphate of zinc for dilute sul- 
phuric acid does not notably change the electro-motive 
force. 

We have said that it did not vary with the richness of 
the solution of sulphate of zinc ; it has been shown that 
there is no perceptible change when the solution is at 
first concentrated and then diluted with one hundred times 
its bulk of water. The thickness or nature of the porous 
jar has no influence ; porous partitions of many kinds 
have been tried, such as gold-beaters' skin, pipe-clay, 
under-baked porcelain, tubes of rosewood and of the 
pear-tree, of ebony and of boxwood. 

Resistance. — It must, however, be acknowledged that 



90 TWO-LIQUID BATTEEIES. 

the condition and force of a battery are always variable ; 
for if at the start the solution is too weak, it becomes 
more and more concentrated, and its condnctivity is con- 
stantly changing. The following figures show that it 
reaches a maximum and then decreases : 

Solution concentrated with sulphate of zinc (specific gravity 

1.441) 5.77 

The same, diluted with its bulk of water , . 7. 13 

The same, diluted with three times its bulk of water 5.43* 

The conductivity of liquids varies also with the tem- 
perature ; that of a solution of sulphate of zinc reaches 
its maximum at 14° cent. 

If the nature of the liquid in the outside jar changes, 
that in the porous jar will also change. In fact, the solu- 
tion of sulphate of copper gradually weakens, and its con- 
ductivity changes with its state of concentration and the 
temperature. 

A few crystals of sulphate of copper may be added in 
the porous jar to keep up the solution. The more con- 
centrated the solution becomes the heavier it gets, and 
in order to keep it in a state of saturation up to the top 
of the jar, they used to suspend crystals to the upper part 
by means of a small diaphragm of copper soldered to the 
strip of copper ; but this precaution has been generally 
abandoned, and the crystals are now simply thrown in 
the bottom of the jar. This suppression causes no incon- 
veniences, because the battery loses none of its qualities 
when the liquid ceases to be saturated ; it is indeed 
an advantage, for the consumption of sulphate is less 
active. 

A saturated solution of sulphate of copper has, how- 

* See table 3, end of volume. 



daniell's battery. 91 

ever, a greater conductivity than when it is diluted with 
water, as the following table shows : 

Sulphate of copper. Saturated solution (specific gravity 1.171) 5.42 

The same, diluted to half 3.47 

The same, diluted to quarter 2.08 

It should therefore be admitted that the use of a 
diluted solution increases the resistance of the battery ; 
but it is probable that the sulphate of zinc in mixing 
with the sulphate of copper increases the conductivity of 
the liquid. 

Endosmose causes the liquid in the porous jar to rise 
slightly above that in the outside jar ; finally, evapora- 
tion causes the. two liquids to gradually descend and in- 
creases the richness of the solution. 

All these reasons, and others which we will soon give, 
go to prove that the resistance of Daniell's battery is 
constantly changing ; every time it is measured it is 
found to be different. 

The intensity of the current of Daniell's battery, as 
has been shown, varies considerably from one day or 
from one hour to another, and as the electro-motive force 
does not change, it is clear that it must be the resistance 
which varies. 

Figures relating to the resistance of battery cells would 
possess but little interest, as they can only be approxi- 
mate, and applicable only to jars and electrodes of deter- 
mined dimensions, and to certain heights of the liquids 
in the jars. 

SELECTION OF CELLS. 

In general, larger cells are used for local circuits, and 
smaller ones for telegraph lines, because the former are 



92 TWO-LIQUID BATTERIES. 

less resistant than the latter ; this difference results from 
the fact that the immersed surface of the electrodes is 
greater in the large ones, whereas their distance is almost 
the same. 

If things were looked at from a physical point of view 
only, the use of large cells would always be advanta- 
geous ; but in the practice there are other things to be 
taken into consideration. The convenience, and above 
all the economy in buying and keeping them in order, 
must be thought of. Large cells are more cumbersome 
and more exposed to accidents ; besides, they are especi- 
ally dear, and the necessary supply of sulphate of copper 
and zinc plates tends to increase the expense. 

Consequently the use of cells as small as possible is 
recommended. It is necessary to understand perfectly 
how in long circuits resisting batteries present but few 
inconveniences, and how the larger cells are preferable in 
short circuits. 

If in a very long circuit, of 3000 units of resistance, 
for instance, with a receiving instrument of 1000 units, 
a battery of 25 cells of 10 units each be employed, the 
total resistance of the battery will be 250 units, and that 
of the whole circuit 4250. The resistance of the battery 
is thus but a small fraction of that of the whole circuit ; 
consequently the substitution of smaller cells, even if 
their resistance were twice as great as that of the first 
ones, would not greatly increase the resistance of the 
circuit, nor, consequently, the intensity of the current. 
But if, on the other hand, we take a short circuit of 2 
units with a receiving instrument of 3 units, and use a 
battery of 5 cells, each having 10 units of resistance, 
there will be in the battery 50 units and in the circuit 55 
units of resistance. 



daniell's battery. 93 

It is seen that the resistance of a battery is the most 
important element, and by diminishing it one half by the 
substitution of larger cells the resistance of the circuit 
will be reduced to 30 units, and consequently the inten- 
sity of the current will almost be doubled. Let us follow up 
this idea. The intensity of the current being much greater 
with the 5 new cells of 5 units of resistance each, their 
number might be reduced to 3, for instance ; the resist- 
ance of the battery would then be 15, that of the circuit 
20, and finally the intensity of the current (^ or ±) would 
be still greater than that we had at the beginning. Thus 
for a short circuit larger cells should be used, only less 
in number, by which a saving is obtained. 

Porous Jars. — The porous partitions which separate 
the liquids in constant batteries are generally made of 
porous porcelain ; but one can use wood, carbon, blad- 
ders, canvas, pipe-clay, paper pulp, and in general all 
substances not chemically acted upon by the liquids. 

In his first experiments Daniell used a piece of bladder 
inside of and having the shape of a copper tube pierced 
with holes, which served as the negative electrode of his 
cell ; this membrane partition presented great advantages, 
its cylindrical form was excellent, and it was very gener- 
ally adopted ; it was very porous and electrically but 
little resistant. It was abandoned because it was too 
porous and too fragile. 

Finally porous jars, properly so called, were brought 
into use ; they are made of porous porcelain. We will 
here only speak of this latter ; those made of parchment 
paper, canvas, etc., will be treated of in the description 
of those batteries in which they are used. 

We have explained how, in the regular and theoretical 
action of Daniell's cell, copper is deposited upon the cop- 



94 TWO-LIQUID BATTEEIES. 

per electrode. In the practice it is found that copper is 
also deposited upon the inside surface of the porous jar, 
and even in the pores, which are finally stopped up ; after 
a certain time the jar ceases to be porous enough and 
should be replaced. That is one of the inconveniences 
of this form of DanielPs cell, which, however, should not 
be exaggerated, as the porous jars are very cheap and 
may be replaced at very little expense. 

In the telegraph service, a porous jar may sometimes 
serve six months or a year. Purchasers of old metals 
buy these porous jars, often very heavily charged with 
copper, and know how to use them to the greatest advan- 
tage. 

These deposits of copper in the interior of the po- 
rous jar frequently present a very interesting peculiarity : 
they show themselves upon the surfaces with a tree-like 
aspect ; it is a slow crystallization, which reminds one of 
the unfolding of a fern. 

It frequently happens that the deposit of copper accu- 
mulates upon certain points of the inside surface, and 
presents a crystalline structure, properly so called. Crys- 
tals are sometimes seen to attain the dimensions of ■£$ or 
■f% of an inch. 

These deposits in the pores and upon the surface of 
the porous jar may easily be accounted for. They are the 
result of an electro-chemical action analogous to that shown 
in a previous experiment by De La Rive upon ordinary 
commercial zinc compared with chemically pure zinc. 
The porcelain contains various heterogeneous particles, 
which produce local actions and also the decomposition of 
the sulphate of copper. It is probable that this deposit 
takes place very slowly at first, but as the deposit accu- 
mulates the process becomes more and more rapid. 



daniell's batteey. 95 

These deposits of copper in and upon the walls of the 
porous partition possess another quality which we should 
not forget ; namely, that of diminishing the internal re- 
sistance of the cell. This is a fact that oft-repeated ex- 
periments have proved. The explanation seems to us 
very clear. The porous partition presents a very great 
electric resistance, because the total section of the canals 
filled with liquid is extremely small. When a portion of 
this section is replaced by copper, a metal possessing 
great conductivity, the resistance should be reduced in 
proportion. 

It should be noted that, under these circumstances, the 
copper causes no polarization of the electrodes, otherwise 
the results would be entirely different. 

All this would lead to the belief that the choice of 
porous jars had great influence upon the intensity of the 
current, by changing the internal resistance of the cell. 
The results of several experiments show, however, that 
jars of different states of porosity can change but slightly 
the resistance of cells. 

The conclusion points to the preference of jars of little 
porosity in all batteries destined for continual and pro- 
longed work. They should be immersed in water before 
charging the battery ; or better, charge the battery sev- 
eral hours before using it, in order to allow the liquids to 
penetrate the pores and come into contact with each 
other. 

Yery porous jars have the disadvantage of allowing the 
liquids to mix too easily ; the result is a direct action of 
the zinc upon the sulphate of copper, and a deposit of the 
copper upon the zinc, which is a grave fault inherent in 
Darnell's battery, and upon which we will now enlarge. 

Local Actions; Waste. — The sulphate of copper, 



96 TWO-LIQUID BATTEKIES. 

which penetrates the porous partition, comes into contact 
with the zinc, and is decomposed by an electro-chemical 
local action. Copper is deposited upon the zinc in the 
shape of black mud, which cannot be put to any use. 
(This black powder is said by some to be oxide of copper, 
but this is an error, as can be easily shown by means of 
some feeble acid, as acetic acid.) 

This action does not co-operate in the production of 
the current ; it takes place especially, as can be easily un- 
derstood, with very porous jars ; but it exists in every ar- 
rangement of Daniell' s cell, as will be seen as we advance. 

This inconvenience would be less if the current circu- 
lated continually ; but in almost all applications, batter- 
ies, and especially those of Daniell, are only used inter- 
mittently and at long intervals. Many of the telegraph 
batteries and those used for electric bells work but a few 
minutes daily, thus being nearly always in an open cir- 
cuit. Under these circumstances, the fault of which we 
speak is at its maximum. 

It is understood that if, on the contrary, the cells are 
very actively employed, as in an important telegraph 
office, this same fault is less grave ; the sulphate of cop- 
per and the zinc are consumed much more usefully. But 
even in that exceptional case, where a Daniell cell fur- 
nishes a constant current, there is a certain quantity of 
sulphate of copper which, penetrating the porous jar, is 
decomposed by its contact with the zinc, and deposits 
upon the latter, copper in the shape of black mud. 

In short, we can say that an ordinary Daniell cell con- 
sumes almost as much zinc and sulphate of copper when 
its circuit is open, and when it does no useful work, as 
when its circuit is closed, and when it really acts as a pro- 
ducer of electricity. 



97 

This is about the only fault that can be found in the 
Dauiell battery. Its gravity, however, has often led to 
the preference, in many instances, of other batteries, such 
as that of Leclanche, which, however, do not fully fill the 
conditions of a constant battery. 

This fault is present in the Daniell battery to a greater 
or less degree, according to the porosity of the jars. 
Among the improvements upon Daniell's battery, which 
we will soon describe, there are some which possess the 
advantage of greatly reducing the detrimental effect in 
question. 

The copper, by entering the pores, diminishes the po- 
rosity, thereby improving the battery, for a certain length 
of time at least. But it is plain that, if the porosity be 
too much reduced, the battery will no longer work, for if 
the pores of the partition are completely stopped up, it 
would no longer furnish any current. 

Finally, the pure loss in the consumption of sulphate 
of copper is less when the solution of sulphate is less con- 
centrated ; and, as the reduction of concentration does 
not diminish the electro-motive force, and does not nota- 
bly increase the resistance, there is a great advantage, as 
can be seen, in not using a saturated solution of sulphate 
of copper. 

It should be noticed that the deposit of copper upon 
the zinc does not change the electro-motive force of the 
cell, which confirms what we said of the constancy of this 
force in Daniell's cell. In some models, the zinc is sus- 
pended, so that it may not rest on the bottom of the jar 
and come in contact with any rubbish that might happen 
to accumulate there, which would result in local actions. 
It is an established fact that, in ordinary batteries, the 
lower part of the zinc is more consumed than that near 



98 TWO-LIQUID BATTEEIES. 

the top. The cause of this is due partly to the contact 
of this rubbish with the zinc, producing local actions. 

Climbing Salts. — The Daniell battery possesses one" 
more little fault that should not be left unnoticed. 
"When the liquid in the outside jar begins to become sat- 
urated with sulphate of zinc, climbing salts are formed, 
which ascend the walls of the outside jar, and even of the 
porous jar, running over the rim of the former and de- 
scending on the outside. All this can, however, be avoid- 
ed by proper care and attention. These salts establish 
permanent communication between the different elements 
of the cell, which communication contributes to the 
waste. The manner in which these salts are formed is 
very easy to understand. 

In the beginning, either by a slight movement or other- 
wise, some of the liquid is thrown upon the sides of the 
jar. Evaporation causes the disappearance of the water 
and leaves crystals. Immediately, capillary action sets in, 
either between the crystals and the side of the jar, or along 
the side of the crystals, and a small quantity of liquid thus 
rises above the general level. 

Evaporation again causes the formation of new crystals, 
which is facilitated by the thinness of the layer. This 
action continues step by step horizontally and vertically. 

As long as the formation of climbing salts does not run 
over the top of the glass jar, or establish any permanent 
communication between the elements, it is not unfavora- 
ble. It might indeed be considered as an advantage, as it 
reduces the concentration of the sulphate of zinc solution. 
We have previously shown by figures that a saturated 
solution has less conductivity than when diluted to half. 
When the solution is saturated, it is incapable of dissolv- 
ing the salt formed by the action of the battery, and the 



99 

most unfavorable thing that can then happen is a deposit 
of crystallized sulphate of zinc upon the zinc or upon the 
immersed part of the porous jar, for it stops the chemical 
action or the communication of the liquids. It is there- 
fore advisable to take the climbing salts completely away 
and not to put them back in the glass jar. 

To suppress the production of climbing salts, it has 
been proposed to spread a thin layer of oil upon the sur- 
face of the liquids, which would check all evaporation ; 
this has, however, received no application, on account of 
the uncleanliness it would inevitably cause. This layer 
of oil would also occasion rapid concentration, which, as 
we have stated, diminishes the conductivity. The climb- 
ing salts may be kept from running over the top of the 
glass jar by smearing the top with some greasy substance 
(paraffin, for instance). 

Climbing salts of sulphate of zinc are very easily de- 
tached from the glass, either with the fingers or with a 
rag ; but they hold much more firmly to the porous jar, 
and it is with difficulty that they may be detached from 
it by rubbing. Therefore, the top part of the porous jar 
which stands out of the liquid should be carefully glazed ; 
the salts may then be taken off as easily as from the 
glass. 

IMPROVED DAOTELL CELL. 

We have sought to construct as satisfactory a Daniell 
element as possible. The following is the disposition 
that we have decided upon : 

The positive electrode is formed of a cylinder of zinc 
surrounding the porous jar, and is heloV at a small distance 
from the latter by means of small sticks of wood placed 
vertically between the two ; the zinc and the small sticks 



100 TWO-LIQUID BATTERIES. 

are held in their place by being tightly bound together at 
the top and bottom with pieces of string. 

The connecting strap of the zinc is cut out of the same 
sheet of metal as the cylinder itself, which dispenses with 
any loss in the cutting, provided two cylinders with their 
connecting straps be cut out of the same piece, one in the 
reverse manner from the other. 

The copper electrode is cut in the same manner out of a 
sheet in the form of a cylinder, which is placed inside the 
porous jar ; small sticks of wood placed around the cojDper 
and bound to it with string keep it from coming into 
contact with the interior surface of the porous jar. 

At two thirds of the height of the copper is fixed, with- 
out solderings and simply fastened in the copper, a circular 
piece of copper pierced with holes, thus forming a parti- 
tion without impeding the movement of the liquid. 
Upon this partition are placed sulphate of copper crystals, 
which hold the solution at saturation. 

In the outer jar is put a solution of sulphate of zinc 
possessing its maximum conductibility ; that is, a solution 
at first saturated and then diluted with its bulk of water 
(specific weight about 1.10). This disposition is intended 
to reduce to a minimum the internal resistance of the ele- 
ment, and to render it as compact and solid as possible. 
For experiments of precision it is best to ascertain, at 
first starting, the density of the sulphate of zinc by means 
of an hydrometer, and to always keep it the same by add- 
ing, from time to time, some pure water, as the solution 
becomes concentrated either by evaporation or by the 
formation of sulphate of zinc in the battery. 

Undoubtedly the use of a saturated solution of sul- 
phate of copper greatly increases the expense of the bat- 
tery, but we are now supposed to be talking of an appara- 



101 

tus designed for experiments of precision and in which the 
question of expense is secondary. 

From this point of view the precautions that we have 
suggested appear to us to be indispensable. How indeed 
could the internal resistance of a cell be advantageously 
measured unless the respective distances between the elec- 
trodes were invariable and the composition of the liquids 
known and determined ? 

It is only with elements arranged in the above manner 
that it may be hoped to obtain concordant or even com- 
parable results. In truth, it is very probable that these 
precautions will not be sufficient, but they are necessary. 

BALLOON BATTERY. 

Another arrangement of Daniell's battery, represented 
by Fig. 22, has been and is still used in some countries. 
It needs no attention for six months, or more, at a time. 
The flask, which surmounts the cell, contains two pounds 
of sulphate of copper crystals, and is filled with water. 
The flask is closed with a perforated cork fitted with a 
glass tube ; this tube descends as far as the liquid in the 
porous jar. The solution of sulphate of copper being 
more dense in proportion as it is more concentrated, it can 
be seen that the part of this solution which is in the po- 
rous jar is constantly held at saturation, for as it weakens 
it is supplied by the saturated solution which descends 
from the flask. 

The glass jar of the cell is closed with a wooden lid, 
which supports the flask. The result is that evaporation 
is reduced to almost nothing, and, consequently, there is 
a very slight or no formation at all of climbing salts, and 
the liquid is preserved. 



102 



TWO-LIQTJID BATTEEIES. 



This battery lias been known to work for more than a 
year without requiring any attention, during which time 
it satisfactorily met all practical requirements. 




Fig. 22. 



It has, however, been replaced by more economical 
batteries, such as Callaud's or Leclanche's. 



A REVERSED FORM OF DAMELL'S BATTERY. 

For a long time Daniell's battery was arranged in a 
manner the reverse of that which we have already de- 
scribed. The zinc, in the shape of a solid cylinder, 
which served as soluble electrode, was placed inside of 
the porous jar, instead of outside. The copper was placed 
around the outside of the porous jar, serving at the same 
time as conducting electrode and as the jar containing 



baniell's batteey. 103 

the liquid. In addition to the exterior hollow copper 
cylinder, another was placed nearer the porous jar, in or- 
der to diminish the resistance of the cell. This interior 
cylinder of copper was pierced with holes, to facilitate 
the circulation of the liquid (solution of copper sulphate). 
Finally, crystals of copper sulphate were put between 
the two copper cylinders, in order to keep the solution in 
a state of saturation, in spite of the consumption of the 
battery. 

At first sight, this arrangement would appear to be 
much superior to that previously described. In this one 
the glass jar is suppressed, and consequently the many 
accidents resulting from its brittleness are avoided. It 
has, however, been abandoned for the first arrangement 
on account of the following reasons : 

1st. The battery with the copper jar costs a great deal 
more, because of the large quantity of copper required, 
and also on account of the quantity of copper sulphate 
with which the battery is charged at the beginning. 

2d. The copper jar might become pierced, and the 
liquid would then leak out ; a few impurities in the metal 
would suffice to set up local electro-chemical actions, and 
thus bring about perforation. 

3d. Cast zinc is used, which presents another disadvan- 
tage. For, during the process of easting, very often little 
cavities are formed in the zinc, into which the liquid pene- 
trates, thereby producing local actions and uselessly con- 
suming the zinc. 

4th. The zinc nearly fills the porous jar, thus leaving 
but little room for the liquid, which is soon saturated 
with the sulphate of zinc and becomes incapable of dis- 
solving any more. This is a grave fault in the working 
of the battery. 



104 TWO-LIQUID BATTERIES. 

We must do Daniell the justice to say that he had 
foreseen this difficulty, and had proposed an accessory 
arrangement for the renewal of the water destined to 
dissolve the sulphate of zinc ; but this addition compli- 
cated the apparatus and increased the cost. 

The cell might be sensibly improved by the substitu- 
tion of a thin, hollow cylinder of zinc for the massive 
zinc used above ; the quantity of water in which the zinc 
is immersed would thus be greatly increased. 

It is well to note, before leaving this subject, that the 
surface of the negative electrode is comparatively much 
larger than that of the soluble electrode. We said, in 
speaking of Wollaston's battery, that this condition was 
very favorable in single-liquid batteries, but it is not so 
in two-liquid batteries, or at least not in Daniell's battery. 
Since the depolarization of the negative electrode is com- 
plete, there is no advantage in increasing its surface. 
The considerations which prevail in the choice of elec- 
trodes have been clearly indicated in that which we have 
just said. 

TKOUGH BATTEEY. 

Still another arrangement of Daniell's battery is rep- 
resented by Fig. 23, and the above name given to it. 

A trough is made of teak and divided into ten cells by 
slate partitions ; each cell is then subdivided by a porous 
partition of unglazed porcelain. A zinc plate is placed 
in one of these divisions, and a thin copper plate in the 
next one, and so on, until the ten cells are occupied. 
The copper plate of one cell is permanently connected 
with the zinc of the next cell by a copper strap cast into 
the zinc and riveted to the copper, which is easily bent 
over the slate partition. 



daniell's batteey. 



105 



The last copper and the last zinc plate are each con- 
nected to brass binding screws or terminals, which be- 
come respectively the positive and negative poles of the 
battery. 

A solution of sulphate of copper and a few crystals are 
placed in the copper divisions ; in the others, pure water 
or a very weak solution of sulphate of zinc. 

This arrangement presents great advantages; it dis- 
penses with glass jars, which sometimes break without 
any apparent cause. The trough is made water-tight by 
coating it internally with marine glue, and the liquids 
ought not to leak out. But it unfortunately happens, 
sometimes, that the marine glue chips off, and one cell 




becomes leaky. When this occurs, the battery must be 
repaired. 

The trough is very solid, and is easily transported when 
not charged with liquid. The zinc and copper electrodes 
of each cell are at a well-regulated distance from each 
other, and do not touch the porous partition if the bat- 
tery is carefully charged. 



106 



TWO-LIQUID BATTEEIES. 



These last conditions are fulfilled with difficulty where 
cylindrical elements are used. The trough having a 
wooden lid, there is very little evaporation. Of all known 
forms, this is the least cumbersome. 

The dimensions of the electrodes are generally, for the 
zinc, 3^ in. by 2 in., and for the copper, 3 in. square. 
The battery will work a month without the necessity of 
opening the trough. One of these batteries of ten cells 
costs $5.25, and the keeping it in order $2 per annum. 



CONVENTIONAL FIGUKE. 

Batteries are generally represented by a conventional 
figure, which originally represented Daniell's trough bat- 



l 





-ililolililil- 



Fig. 24. 



tery, or the sand battery, of which we spoke in Part I. 
Each cell is represented by two lines (Fig. 24), the short 
and thick one representing the zinc, and the long and 
narrow one the copper. Z and C mark respectively the 
negative and positive poles of the battery. 



daniell's batteey. 



107 



MITIBHEAD'S BATTEEY. 

There are a great many such in use in England. 

The outside jar is made of white porcelain and is 




square. The porous jar, made of red earthenware, con- 
tains the negative electrode and the sulphate of copper, 



108 TWO-LIQUID BATTERIES. 

and is placed in the square porcelain jar, which contains 
the zinc electrode and the sulphate of zinc. The elec- 
trodes are the same as in the preceding battery. 

For economical reasons these cells are taken by twos ; 
that is, each outside porcelain jar contains two compart- 
ments and two complete cells. This arrangement pre- 
sents a very favorable condition, which is also met with 
in the cylindrical cells described at the beginning ; viz., 
the compartment containing the sulphate of zinc is quite 
large. Fig. 25 represents several of these cells together, 

CAEEfi'S batteey. s 

Carre's battery differs from the ordinary Daniell bat- 
tery simply in the substitution of a vessel made of 
parchment paper for the ordinary porous jar. This 
porous partition offered very little resistance, which re- 
alized the object of its inventor. The whole battery 
indeed was arranged with a view to diminishing the re- 
sistance. The zinc cylinders were 22 in. high and 4£ in. 
in diameter. 

Sixty of these cells were used by M. Carre for electric- 
light purposes, which is, we think, worthy of mention, 
as it was the first time that Daniell's battery had been tried 
in that way. 

In fact, M. Carre's arrangement was only fit for elec- 
tric-light purposes ; that is, to furnish a continuous cur- 
rent of great intensity for several hours. The frailty of 
the porous partition rendered the battery useless for any 
work of long duration. We believe, however, that this 
battery, in spite of the disadvantage we have pointed 
out, should again be taken up by persons interested in 
the electric light, who could give it a fixed place and 



DANIELlAs BATTERY. 109 

could take care of it. In the use of this battery, the dis- 
agreeable acid vapors, which are dangerous to inhale, 
would be avoided, and the expense would be compara- 
tively small. 

This battery has been known to work 200 successive 
hours without any sensible weakening, by carefully re- 
placing, every 24 hours, a part of the sulphate of zinc 
with pure water. 

SIEMENS AND HALSKE'S BATTERY. 

This battery is a Daniell battery with a porous jar, 
like those which precede, and is very extensively em- 
ployed in Europe. 

The copper, c, is at the bottom of the glass jar (Fig. 26), 
and the diaphragm or porous jar has the form of a bell. 
A thing to be noted is the central chimney, in which 
there is a glass tube through which a copper wire, at- 
tached to the negative electrode, passes, forming the con- 
nection of the positive pole. The porous jar sustains a 
mass of paper pulp, dampened with sulphuric acid, and 
then dried. The zinc, 2, placed on top of the pulp, is a 
very thick cylinder, melted in a mould and carrying a 
vertical appendix, to which the positive connection of 
the adjoining cell is attached. 

The arrangement of this battery has been changed 
several times. At first there was no porcelain porous 
jar, but simply the paper pulp. The general character- 
istics, however, have remained the same. The great 
thickness of the porous jar suppresses almost completely 
the diffusion of the sulphate of copper, and consequently 
the waste chemical action and the useless consumption of 
zinc and sulphate of copper are avoided. On the other 



110 



TWO-LIQUID BATTERIES. 



hand, however, the internal resistance of the cells is con- 
siderable, so that they cannot be used as local batteries. 




Fig. 26. 
TABLET'S BATTEET. 



Cromwell Varley suggested a means of completely sup- 
pressing the passing of the sulphate of copper through 



Ill 

the porous partition, a tiling which Siemens and Halske 
only slightly diminished and slackened. This means con- 
sists in the substitution of oxide of zinc for the paper 
pulp in the preceding battery. It is easily understood 
that the sulphate of copper, which enters the mass of 
oxide of zinc, forms sulphate of zinc, and deposits oxide 
of copper in the shape of a black powder. 

This original idea was perhaps never put into applica- 
tion outside of Varley's laboratory. But it deserves 
notice, for it shows the reader what an infinite variety 
of resources chemistry presents to those who know how 
to search for them. 

It is clear that this porous partition becomes destroyed 
in time ; it is also very resistant. These "are all incon- 
veniences in daily practice, but are unimportant in labo- 
ratory experiments, which require as perfect a battery as 
possible. 

MINOTTO'S BATTEEY. 

This is in form a Daniell battery, extensively used in 
Italy and throughout British India. It consists of a jar, 
at the bottom of which is a copper plate fitted with a 
wire covered with gutta-percha, which ascends to the 
top of the jar and serves as a* connection. This electrode 
is covered with an inch of crushed sulphate of copper, 
this again with a layer of river sand, and finally a plate 
of zinc of considerable thickness. The crushed sulphate 
of copper is separated from the sand by a piece of 
cloth or blotting-paper. Sir William Thomson recom- 
mends sawdust instead of sand. The zinc is of con- 
vex form, in order to permit the freeing of bubbles of 
hydrogen which sometimes form themselves in DanielPs 
battery. 



in 



TWO-LIQUID BATTEKIES. 



These batteries last eighteen or twenty months upon 
important telegraph lines, and as long as thirty-two 
months upon less important lines. 

TKOUYE'S BLOTTING-PAPEK BATTEEY. 

Trouve's battery is one of the latest modifications of 
Daniell's battery. Fig. 27 represents a separate cell. 




Em. 27. 

At the top there is a plate of zinc, at the bottom a 
plate of copper, and between the two a considerable 
thickness of blotting-paper. The upper half of the blot- 
ting-paper is wet down wh*h a concentrated solution of 
sulphate of zinc, and the lower half with sulphate of 
copper. We have, therefore, all the elements of a Daniell 
battery. 

It is of course plainly understood that when this bat- 
tery is perfectly dry it is absolutely inert. To make a 
source of electricity, or, more simply, a voltaic cell, water 
must be added ; only that quantity which the paper can 
absorb is necessary. Thus there is no free liquid, and 
Trouve might have called his battery a moist battery, in 



daniell's battery. 113 

order to distinguish it from liquid batteries properly so 
called. 

Let us return to the description of the cell. The two 
electrodes and the blotting-paper are held by a central 
piece of copper, insulated by a tube of ebonite, which 
goes above the zinc and penetrates the cover of the glass 
jar, whose edges should be well ground in order to pre- 
vent all evaporation. This central piece of copper is 
finally furnished with a binding screw, to which the con- 
nection of the adjoining cell or of the circuit is fastened ; 
the negative pole is a copper wire soldered to the upper 
part of the zinc electrode. 

Several advantages of this battery are easily seen. 
When it is dry there is no w T aste whatever, although it be 
charged. To dry it, it is only necessary to expose it for 
a few hours to the sun or to a current of air. If it is to 
be used, the elements must only be moistened. If the 
cells are separated from each other like the one repre- 
sented in the figure, they must be put under the faucet of 
a fountain which runs slowly. This operation should be 
repeated after a short interval, in order to allow the first 
water to saturate the. paper to the centre. The cell is 
sufficiently moist when, by pressing the zinc and the 
copper between the thumb and index, drops of water are 
seen to ooze out upon the surface of the paper. When 
several cells are attached to the same cover, as in the 
military or medical batteries which we will describe far- 
ther on, they are immersed in special vessels and left 
there about a half-minute. Whatever the method be 
(and the choice is not of much importance) of moist- 
ening the elements, this done, they are placed in the 
glass jar or in the ebonite box, where they may re- 
main several months, always ready for work, and indeed 



114 TWO-LIQUID BATTEEIES. 

continually working and furnishing a remarkably regular 
current. 

This regularity constitutes a new advantage in Trouve's 
battery, upon which we will insist before passing to its 
applications. 

The liquids of ordinary batteries have a movement but 
slightly impeded by the porous jar, which results in their 
mingling, as we have several times explained. The con- 
sequence is that local actions, which disturb the normal 
working of the battery, take place and occasion waste. 

In Trouve's arrangement the movement of the liquid 
is almost suppressed, consequently there is very little 
mixing of the sulphate of copper with the sulphate of 
zinc, and there are scarcely any local actions ; that is, there 
is no reduction, of the sulphate of copper upon the sur- 
face of the zinc. An evident economy of matter con- 
sumed by the battery, and other interesting facts, are the 
results. The liquids keep their respective positions al- 
most without mixing, the resistance varies very slowly, 
and consequently the intensity of the current possesses 
great constancy. 

"We have often made the following experiment with a 
Daniell porous-jar battery. Having closed the circuit in 
the evening .upon a galvanometer, it was found in the 
morning, twelve hours later, that the deflection was ex- 
actly the same. But if the circuit were opened only one 
minute and then again closed, there was observed a nota- 
ble difference. 

If the same experiment be made with Trouve's bat- 
tery, the intensity of the current is found to be the same, 
after the momentary rupture of the circuit, as it was be- 
fore. 

This difference in the results shows that the variation 



daniell's battery. 115 

of the resistance takes place suddenly and abruptly in the 
ordinary Daniell cell, and on the other hand very slowly 
in Trouve's arrangement. 

We have insisted upon the constancy of the electromo- 
tive force of Daniell's battery in general. Under the 
form given to it by Trouve is added that very important 
quality which consists in the existence of a slightly varia- 
ble resistance. 

Recharge of the Cell. — When the cell has w r orked 
several months, more or less, the sulphate of copper is 
used up and converted into sulphate of zinc, and in order 
to give to the cell its first energy it must be recharged in 
the following manner : 

The sulphate of zinc, which has taken the place of the 
sulphate of copper in the lower half of the paper, must 
be dissolved in pure water. For this purpose there are 
especial vessels having the desired level of the water 
marked upon their sides, for the sulphate of zinc which 
is in the upper half must not be dissolved. This same 
vessel must then be filled to the same level with a warm 
saturated solution of sulphate of copper, in which the 
lower half of the elements are immersed and left there 
three or four minutes. At the end of this time the sul- 
phate will have penetrated from the circumference to the 
centre of the paper, and the cell is recharged. The cell 
should then be left to dry, and when it is to be used 
it should be dampened as we have said in the begin- 
ning. 

Military Battery. — Trouve's battery has been ap- 
plied in military telegraphing and with very good results. 
This battery consists of nine cells, distributed in three 
boxes, each containing three cells, as shown in Fig. 28. 
The boxes are made of ebonite, and have slate lids, to 



116 



TWO-LIQUID BATTERIES. 



wliich the cells are attached as in the separate cell, Fig. 
27. The three boxes are then placed one above another 
in the desired order, and enclosed in a large oaken box. 
This outside box is carried by means of a strap thrown 




Fig. 28. 



over the shoulder, or placed upon a wooden frame fas- 



tened on the back. 



The cells are 2J- in. in diameter 



and 1^- in. in thickness. 

Medical Battery. — For the medical application of a 
continuous current, Trouve arranged a battery of three 
small cells, each being about an inch in diameter and 1-j. 
in. in thickness. The result shows a considerable re- 
sistance. These cells are taken by forties, sixties, or 
eighties, and attached to a single piece of slate, and placed 
in a water-tight wooden box, to the cover of which the 
connections are fastened, so that the whole or only part 
of the battery may be used at will. 

These cells last a long time, because they contain a 



daniell's battery. 117 

comparatively great quantity of sulphate of copper, and 
because they work in circuits of very great resistance. 

There is a very decided advantage in their great in- 
ternal resistance for medical purposes ; for the quantity 
of electricity which circulates is very small, and the 
electro-chemical decomposition at the contact of the con- 
ductors with the body of the patient is insensible. 

Resistance in Trouve's Battery.- — The largest model 
yet made is 3^ in. in diameter and 2-^ in. in thick- 
ness. It is understood that, with this thickness, the re- 
sistance of the cell is inversely proportional to the sec- 
tion of the disc electrodes. The regular form of these 
cells is much more convenient than that of ordinary 
liquid batteries for exact calculations. 

By modifying the diameter of the electrodes and the 
thickness of the blotting-paper between them, the resist- 
ance may be regulated at will. 



CHAPTER II. 
GRAVITY BATTERIES. 

Several physicists became possessed, at the same time, 
of the idea of suppressing. the porous jar, and of separat- 
ing the liquids by their difference in density. Notable 
among these physicists were Callaud, Meidinger, and 
Yarley. The last mentioned took out a patent before 
any of his competitors, in 1855. 

Callaud's Battery. — This battery has been greatly 
improved since its first appearance. The following are 
the dimensions of the one most in use : 

From the top of a glass jar 8 in. high is suspended a 




cylinder of zinc 2 in. high. It is held by three hooks 
riveted in the zinc and resting on the rim of the jar. 
The copper electrode is formed of a thin strip of copper 



GRAVITY BATTERIES. 119 

rolled in the shape of a cylinder 1J in. high and 1J in. 
in diameter, and is placed at the bottom of the jar. A 
copper wire covered with gutta-percha and riveted to 
the copper cylinder passes through the liquid, and being 
twice bent, is soldered to the zinc of the adjoining cell. 
If the wire were not insulated by the gutta-percha, it 
would be liable to be cut at the line of sej^aration of the 
two liquids.* 

The solution of sulphate of copper is at the bottom of 
the jar, and remains there, because it is heavier than that 
of sulphate of zinc, which is placed above. 

Charge and Maintenance. — The zinc being put in 
place, fill the jar to within half an inch of the top of the 
zinc with water containing one tenth of a saturated solu- 
tion of sulphate of zinc. In general, when the solution 
of sulphate of zinc is poured in the water, the latter be- 
comes slightly cloudy, which is the result of the presence 
of a small quantity of carbonate of lime in the water, es- 
pecially if well-water ; the addition of the sulphate of 
zinc brings about a reciprocal action ; carbonate of zinc is 
formed, and sulphate of lime is precipitated. But this 
precipitate, being in a very small quantity, remains a long 
time in suspension, during which time the whole liquid 
assumes an opaline tint. At length the sulphate of lime 
falls to the bottom of the jar. It does not sensibly alter 
the action of the battery. 

The sulphate of copper is added by means of a siphon. 
The solution, prepared beforehand, is conducted to the 
bottom of the jar and increased until the water is within 

* This is explained by a local action, the formation of a cell be- 
tween the two liquids and the copper wire. It will be seen farther 
on that a current can be produced under these circumstances, and 
the natural result is that the copper is dissolved in one of the liquids. 



120 TWO-LIQUID BATTEKIES. 

a quarter of an inch of the top of the zinc. The sul- 
phate of copper does not remain separate at the bottom 
of the jar ; it mingles with the lower part of the rest of 
the liquid, and consequently it is a diluted solution and 
not a saturated one, which surrounds the negative elec- 
trode. We have already said, in speaking of the porous- 
jar battery, that a saturated solution presents no advan- 
tage and only renders the local action more energetic. 

The quantity of sulphate mentioned is sufficient for 
one .month. A too great weakening of the solution may 
be recognized by the discoloration of the lower stratum 
of liquid. 

When the solution of sulphate of copper is again add- 
ed, it is better to take off about a quarter of an inch from 
the top of the water, unless evaporation has already low- 
ered the water, in which case some pure water should be 
added, in order to reduce the concentration of the sul- 
phate of zinc. 

It is best to examine the battery every three months ; 
but if it is properly taken care of from month to month, 
it need only be thoroughly cleaned once a year. When 
this is done, the deposits formed upon the surface of the 
zinc should be scratched off, the jars washed, and the 
liquids renewed as in the beginning. 

We add that twenty-six batteries, eighteen cells in each, 
distributed in as many stations, caused an expense of fif- 
teen cents yearly for each cell. This result, calculated 
upon three years' experience, has the value of practical 
information. 

Loc^l Actions and Lost Work. — Daniell's gravity 
battery is not free from that great fault that we have 
indicated, which consists in the local chemical actions 
which do not co-operate in the production of elec- 



GRAVITY BATTERIES. 121 

tricity, and which even take place when the circuit is 
open. 

The two liquids, one above the other, would mingle 
extremely slowly if it were not for several causes, which 
we will examine. If a gravity cell be closely observed, 
the formation of gaseous bubbles at the contact of the 
zinc, and even upon the surface of the copper electrode, 
is seen, and these bubbles, freeing themselves from time 
to time, produce an agitation of the liquid. Indeed, two 
distinct currents in the liquid are seen, descending on one 
side and rising upon the other, which brings about a very 
slow mingling of the liquids. We will again have occa- 
sion to speak of these bubbles of gas and their effects ; it 
suffices for the present to observe the movement they 
produce in the liquid. The result of this movement is 
that a small quantity of sulphate of copper ascends to the 
top. This salt decomposes at the surface of the zinc ; 
copper is deposited, and an equivalent quantity of zinc is 
dissolved. The copper generally attaches itself to the 
lower part of the zinc, and frequently in the shape of 
pendants or stalactites, which hang below the zinc. The 
longer these pendants become the more rapidly they 
grow, and if they reach the level of the sulphate placed 
in the bottom of the jar, the battery becomes rapidly ex- 
hausted. It is, therefore, very advantageous to detach 
these stalactites, which can be done, when the battery is 
examined, by sharp taps on the zinc. The zinc should 
be in a perfectly horizontal position; for if one side were 
lower than the other, pendants would form themselves 
rapidly on the lower side. 

Resistance of Callattd's Cell. — There are two sizes 
of Callaud's cell in use, one of which is much larger than 
the other ; but the separation of the electrodes balances 



122 TWO-LIQUID BATTERIES. 

the difference in the dimensions, and the two cells have 
sensibly the same resistance. 

This resistance has been observed to vary from 37 nnits 
at the beginning, when the water contains very little sul- 
phate of zinc, to 5L|- units after 23 days' work ; that is, 
when a considerable quantity of sulphate of zinc has been., 
formed. These figures confirm that which we have pre- 
viously said of the Daniell gravity cell ; no exact figures 
even for batteries of well-determined dimensions can be 
given; only vague limits between which the resistance 
varies can be fixed upon. At all events, Callaud's cell 
should be considered as possessing a very feeble resist- 
ance, and as w T ell adapted for local as for long and resist- 
ant circuits. 

APPLICATIONS OF CALLAUD'S BATTEKY. 

This battery was not very extensively used by the Eng- 
lish, because they claimed that, to work well, it should 
not be moved at all. This, however, should not be exag- 
gerated, as in France the battery is placed in a box upon 
rollers. The box remains under the table during work, 
and is only pulled out when the battery is to be examined 
or recharged. This movement has no sensible effect upon 
the working of the battery. 

It has been adopted in Italy with a slight modification. 
The glass jar, instead of having the shape of the ordinary 
one, is compressed in the middle, thus dividing it into 
two compartments. The zinc rests upon the border of 
this partition. The diameter of the jar at the top and 
bottom is four inches, and that of the middle portion is 
only two inches. These dimensions would seem to in- 
crease the resistance, without presenting any counterbal- 



GRAVITY BATTERIES. 123 

ancing advantages. The dimensions of the Italian bat- 
tery are smaller than those of the French model ; but 
such as it is, it has for several years given great satisfac- 
tion, as much on account of its constancy as on account 
of the economy and facility of keeping it in order. 

This battery is very extensively employed in the United 
Stales. The monthly expense of keeping in order 600 
Callaud cells, distributed in three batteries which supply 
ten circuits, is about $30. 

There is another modification in use in the United 
States, to which Mr. Lock wood, its author, has given his 
name. The peculiarity of this form consists in the use 
of two flat helices as the copper electrode. One of these 
helices is placed at the bottom of the jar, and the other 
above the sulphate of copper. This disposition certainly 
renders the resistance of the battery less. Lockwood 
uses crystals of sulphate of cojDper, which, according to 
our view, uselessly increases the cost and the local ac- 
tions. 

TEOUVE-CALLAUD BATTEKY. 

Tror.ve arranged a Daniell gravity battery, which is 
extremely cheap. Trouve had in view the application of 
his battery to medical purposes — it furnishes a continu- 
ous current — which is at present used in many hospitals 
and by many physicians. It could also be very well em- 
ployed for other purposes. The glass jar is 4f in. high 
and 2f in. in diameter. The zinc is held upon the rim 
of the jar by being bent over in three places by means of 
pincers. The negative element consists of a copper wire 
in the shape of a flat helix, which rises in a glass tube to 
the top of the jar. The connection* between the cells is 
made by means of a spiral spring at the end of the wire 



124 



TWO-LIQUID BATTERIES. 



which is soldered to the zinc, and to which is fastened the 
wire forming the connection of the adjoining cell. 

This battery, shown by Fig. 30, differs but slightly 




from the one we have described above ; but it is very 
simple in arrangement, and on account of its smajl di- 
mensions each cell costs only 12 cents. 



MEIDINGEK'S BATTEEY. 

This is one of the most extensively employed batteries 
in Germany. It has been tried in many other countries, 
but has been finally abandoned for the following reasons : 
Its cost is greater than ordinary Daniell or Callaud bat- 
teries ; its internal resistance is also greater, and it occu- 
pies a considerable space. 

The Meidinger batteiy (Fig. 31) consists of a large 
glass jar, A, at the bottom of which is placed a cup, d. In 
this latter is the negative element, formed of a thin leaf 
of copper, c, rolled in the shape of a cylinder, from which 
a copper wire rises in a gutta percha tube, g, to the top of 
the vessel, and forms the positive connection of the cell. 

The cylinder of zinc, Z, is suspended above, as shown in 



GRAVITY BATTERIES. 



125 



the cut, and descends a little below the top of the cop- 
per. The two jars are filled with liquid. The glass tube 
A, pierced with holes at the bottom, is placed in the cen- 
tre of the cell, with the lower part in the cup ; this cen- 
tral tube is filled with sulphate of copper crystals. The 
sulphate of zinc, being lighter, remains above the dissolved 
sulphate of copper. At the beginning, in order to in- 
crease the conductivity, magnesic sulphate is put in the 




Fig. 31. 

water, which solution has greater conductivity and is less 
dense than that of sulphate of copper. 

The advantages of this battery are as follows : 
1. It contains a large quantity of water which is re- 
quired to dissolve the sulphate of zinc formed. In order 
that the battery may work a long time without any atten- 
tion, this condition is very essential. We will see far- 
ther on that, when the solution of sulphate of zinc ap- 
proaches saturation, it becomes more dense than that of 
copper, and that consequently the relative positions of 
the liquids are apt to change. 



126 TWO-LIQUID BATTEEIES. 

2. The deposits of copper which form upon the sur- 
face or hang in stalactites from the lower part of the zinc 
fall outside of the centre cup and thus do not touch the 
solution of sulphate of copper ; this contributes greatly 
to the cleanliness and good condition of the battery. We 
have seen (in speaking of Callaud's battery) that, when 
these stalactites touch the solution of sulphate of copper, 
local action increases rapidly and assumes a very injurious 
intensity. This latter inconvenience is avoided in Meidin- 
ger's battery. 

3. The cover which closes the cell and. which is neces- 
sary to support the glass tube (sulphate of copper reser- 
voir) almost completely prevents evaporation. 

4. A first inspection will show whether the sulphate of 
copper is used up or not ; the electro- motive force is kept 
up until the last crystal has disappeared and the resist- 
ance rather diminishes. 

Lately, Meidinger has replaced the copper with lead. 
This does not in any way alter the nature of the chemical 
action, for the electrode soon becomes covered with the 
deposit of copper. The copper wire which serves as the 
connection is also replaced by a strip of lead, which in- 
deed needs no protection, for lead is not attacked by the 
licjuids which enter into the composition of the battery. 

The only advantage in the substitution of lead for cop- 
per is that it reduces the cost of the battery. 

We have already spoken of the disadvantage in keep- 
ing the solution in a state of saturation ; we find a confir- 
mation of our opinion in the following fact : The ad- 
ministration of Berlin recommends not to recharge the 
cells until the last crystal of the preceding charge has 
disappeared and not to put in too large a quantity of sul- 
phate of copper. 



GEAVITY BATTERIES. 127 

A commission chosen by this administration observed, 
also, that the economical coefficient diminished when the 
cells were too frequently charged or with too great a quan- 
tity. 

According to our view, there should have been a com- 
plete suppression of crystals. We will soon see that the 
commission arrived at a contrary conclusion ; it preferred, 
it would seem, to sacrifice the economy of the material 
and to diminish the work of the operators. 

Dr. Dehms reports the resistance of Meidinger's ele- 
ment as varying from 4 to 9 of Siemen's units,* according 
to the models. 

MEIDINGER'S FLASK BATTERY. 

Instead of the interior tube reservoir, Meidinger has 
finally adopted a large exterior flask as reservoir for the 
crystals (Fig. 32). This form has been iu use a long time 
in Bavaria and Germany, where it was recommended for 
branch telegraph offices and for the following reasons : 

1. In all branch offices (in Northern Germany) contin- 
uous currents are employed ; the consumption of the bat- 
tery is therefore considerable, and if the labor of fre- 
quently renewing the elements is to be spared, a battery 
should be adopted which contains a large quantity of ma- 
terial. This is found in the battery in question, as the 
flask holds two pounds of sulphate of copper. 

2. The disappearance of the charge of sulphate of cop- 
per is here more plainly seen than in the other model, 
and cannot escape the most rapid glance. 

3. In these branch offices the battery is rarely made to 

* A Siemen's unit is equal to the resistance offered by one metre of 
mercury whose sectional area is one millimetre. 



128 



TWO-LIQUID BATTEKIES. 



work simultaneously upon several lines ; therefore its re- 
sistance, which is considerable (10 of Siemen's units to 
each cell of the approved form), presents but little incon- 
venience. 

Under these two forms, Meidinger's battery is employed 




Fig. 32. 

in the railway and state telegraph services of Russia, al- 
most to the exclusion of all others. 

The batteries are generally left one year without care, 
in some instances fourteen months. But in offices where 
there is a very active service, the sulphate of copper is 
renewed every four or six months. 



KKUGEK'S BATTERY. 

This is a battery said to have advantages over other bat- 
teries without the porous jar. The zinc is placed as in 
Callaud's ; but the copper has the form of a hollow cylin- 
der, and is placed vertically in the jar and has the same 



GRAVITY BATTERIES. 129 

height. The cylinder is made of a very thin piece of 
copper, cut longitudinally at the bottom in six places ; 
the divisions thus formed are bent outward and hold the 
cylinder in the centre of the jar. There are also three 
pegs fastened in the zinc, which serve to keep the copper 
cylinder in place. 

If sulphate of copper crystals are added, they are placed 
in the copper cylinder and the solution formed remains at 
the bottom of the jar. 

This disposition costs less than that of Meidinger, and 
produces a battery with much less resistance ; in this re- 
spect it is preferable to Callaud's, but costs more. 

We know, however, from good authority, that this 
battery presents a grave inconvenience. The copper be- 
comes eaten at the line of separation of the two liquids, 
and at the end of a certain time it breaks. It will be re- 
membered that we mentioned, when speaking of Callaud's 
battery, the necessity of protecting with gutta-percha the 
copper wire which traversed the liquids and served as the 
connection. 

This inconvenience could be avoided by substituting 
lead for the copper, as Meidinger sometimes does. 

In the first edition of this work we expressed the opin- 
ion that the portion of copper which is not immersed in 
the solution of sulphate of copper tends to increase the 
internal conductivity of the element, although it takes 
no part in the regular chemical action which produces the 
current. Since then, Mr. G. d'Infreville has sent us the 
very interesting results of his experiments upon this sub- 
ject. He has found that this disposition causes a diminu- 
tion in the electro-motive force. This will not seem sur- 
prising to physicists, for they will readily understand that 
in Krager's or any analogous battery the circuit becomes 



130 



TWO-LIQUID BATTERIES. 



closed by the sulphate of zinc at the top ; a constant de- 
rived current is thus produced, and consequently the dif- 
ference of potential is diminished between the electrodes, 

SIK WILLIAM THOMSON'S BATTEEY. 

This illustrious physicist invented a very original dis- 
position of the Daniell gravity battery. The elements are 
piled up one upon another as in Volta's column battery 
or as in Marie Davy's sulphate-of-lead battery. 

These elements (Fig. 33) consist of wooden trays, lined 




Fig. 33. 

on the inside with lead to make them, water-tight. At 
the bottom of each tray is placed a thin plate of copper. 
In the four corners of this square tray are little blocks of 
wood which support the zinc electrode. This latter has 
the singular form of a gridiron, having its bars very close, 
but still leaving space enough between for the circulation 
of the liquid. The feet of this gridiron are turned up- 
wards, supporting the cell above. 

In some instances the zinc is wrapped in parchment 



GEAVITY BATTERIES. 131 

paper, thus constructing a porous jar which prevents the 
mingling of the liquids ; this may, however, well be dis- 
pensed with. 

The connection between one cell and the following one 
is simply obtained by their weight, which presses the lead 
on the bottom of each tray upon the four corners of the 
zinc below. 

Care must be taken in charging the cells, to place them 
in a perfectly horizontal position ; this can be easily as- 
certained by pouring some water in the tray and observ- 
ing if it spreads equally over the bottom. 

The sole advantage of this form is the feeble resistance 
it gives to the cells. It is used as local battery in the 
submarine telegraphs, where Sir William Thomson's 
" Siphon Recorder " is at work. "We are informed that 
it is also employed in Russia, and has indeed been applied 
for electric light purpose. 

The battery should be charged with a solution of sul- 
phate of zinc, whose density is 1.10 and the sulphate of 
copper crystals are placed as regularly as possible all 
around and at the bottom of the tray. 

Scarcely more than eight or ten cells can be piled up 
in one column, and a series of these columns are con- 
nected by very large conductors. If the battery ifc used 
in delicate experiments or for the working of the 
" Siphon Recorder,'' it must be constantly watched, and 
a little of the sulphate of zinc solution taken out daily 
and replaced with pure water. If possible, the density 
of the liquid should be kept between 1.30 and 1.10 ; for 
that purpose it should be measured from time to time 
with an hydrometer. 

The circuit of the battery should always be closed, in 
order to avoid the deposit of copper upon the zinc. It 



132 TWO-LIQUID BATTERIES. 

is advisable when the battery is not in use to keep it in 
short circuit, so that the sulphate of copper may be 
rapidly exhausted. 

It is perhaps a good idea to measure, now and then, 
the electro-motive force of each series and of each cell 
separately. When one cell is found to have lost much, 
on account of the deposit of copper upon the zinc, it 
should either be taken away entirely or placed in short 
circuit, to get rid of the useless resistance it introduces 
into the circuit. 

Sir "William Thomson has, besides, given an inverse 
form to his battery, upon the basis that a saturated solu- 
tion of sulphate of zinc has a density of 1.44, whereas a 
saturated solution of sulphate of copper has a maximum 
density of 1.18 ; the sulphate of zinc is below and the 
sulphate of copper is above, the contrary of that which 
prevails in all preceding batteries. We have not been 
able to obtain any notes that the eminent author may 
have published upon the subject, and do not therefore 
know his motives for this reversed form. We only know 
that it is practically inconvenient, and presents the fol- 
lowing fault, viz., that reduced copper falls upon and 
finally covers the zinc. It is possible, however, that this 
reversed form possesses great advantages for special cases. 

The principle of this form deserves notice. It is seen 
that if, in ordinary gravity batteries, the sulphate-of-zinc 
solution is permitted to approach or to arrive at satura- 
tion, the two liquids are no longer separated by their 
difference in density in the desired manner ; the result is 
that the battery works badly and there is considerable 
waste. 



GRAVITY BATTERIES. 133 



ELECTRO-MOTIVE FORCE OF THE DANIELL 
GRAVITY BATTERY. 

At first it would seem that the electro-motive force of 
the Daniell battery ought to be the same, with or with- 
out the porous jar. The results of all measurements 
show, however, the superiority of the gravity battery. 
One might believe that these differences arise from 
errors of observation : but we have assured ourselves by 
a direct comparison made by the method of opposition 
that the electro-motive force of gravity cells is the same 
in models differing widely from each other, and that it is 
much greater than that of a cell with the porous jar. 

This is a peculiarity difficult to explain, unless a feeble 
polarization at the surface of the porous jar be admitted. 

It must undoubtedly be placed with that other fact of 
which we have spoken ; viz., the electro-motive force of 
Daniell's porous-jar element is very inferior to its normal 
value when it is first mounted and when the imbibition 
of the porous jar is not yet complete. 



CHAPTEE III. 
GENERAL REMARKS UPON DANIELL BATTERIES. 



AMALGAMATION OF ZINC IN THE DANIELL 
BATTEEY. 

"We have, from the beginning of this work, shown the 
advantages of amalgamated zinc over commercial zinc 
when immersed in dilute sulphuric acid. 

"When, therefore, a Daniell battery is charged with 
dilute sulphuric acid, there is a great advantage in the 
use of amalgamated zinc ; but to-day the acid is mostly 
suppressed and replaced by sulphate of zinc. It is gen- 
erally believed that it is still advisable in this case to 
amalgamate the zinc, but we have informed ourselves as 
to the subject, and find that the addition of mercury is 
rather injurious than useful. 

We have taken several cells, one having amalgamated 
zinc, joined them in intensity, and allowed them all to 
undergo the same alternatives of rest and action. At 
the end of fifteen days it was found that the local action 
had been much greater upon the amalgamated zinc than 
upon the others ; that is, the deposit upon the surface of 
the zinc and at the bottom of the jar was more abundant 
in the amalgamated cell. 

To confirm this result we have made the following 
experiment,. like that of De La Rive : We put a piece 



KEMAKKS UPON DANIELL BATTERIES. 135 

of well-amalgamated zinc in a solution of sulphate of 
copper ; the attack took place immediately and rapidly ; 
.in twenty minutes all the sulphate of copper was decom- 
posed. 

These experiments possess no other interest, however, 
than that of justifying the general practice adopted by 
those who use the Daniell battery without free sulphuric 
acid ; that is, in the electric telegraph and analogous appli- 
cations. 

Experiments of Jules Regnauld give the following 
figures for the electro-motive forces of the batteries in 
question : 

Pure zinc, sulphate of zinc, sulphate of copper, copper. . . . 175 

Amalgamated zinc, sulphuric monohydrate, 1 vol. 

Water, 10 vol. ; sulphate of copper, copper 179 

It is therefore clear that the use of amalgamated zinc 
in acidulated water occasions a slight increase of the elec- 
tro-motive force ; this superiority, however, which is less 
than 2|- per cent, has but little practical interest. 

COPPER-PLATING. 

The study of Daniell's battery has led to the creation 
of a vastly important industry ; namely, that of copper- 
plating. Its object is the reproduction in copper of 
artistic or mechanical models, typographic blocks, med- 
als, bas-reliefs, statuettes, etc. etc. 

Jacobi in Russia, and Spencer in England, having 
observed that the copper which is deposited upon the 
copper electrode was so fine as to reproduce the smallest 
irregularities of surface of that electrode, decided to 
make use of this process of moulding, and they have 



136 TWO-LIQUID BATTERIES. 

shown its great utility. The extreme facility of the pro- 
cess renders it accessible to every one, and consequently 
its use has spread with infinite variations. 

We shall not enter upon the details of this process, 
but only show the most simple method of copper-plating, 
which consists in the use of a large Daniell cell with the 
porous jar. The porous jar contains the amalgamated zinc 
immersed in well-acidulated water. In the outside jar, 
which is comparatively much larger, is a saturated solution 
of sulphate of copper and electrodes formed of pieces of 
gutta-percha moulded upon the model (medal or wood- 
engraving). To the surface of these gutta-percha moulds 
is imparted a conductive quality by means of an im- 
palpable powder of plumbago spread upon., it with 
brushes. An exterior conductor joins the zinc to the 
negative electrode. The deposit commences directly and 
is very slow at first upon the plumbago, but as the copper 
accumulates the process advances at a more rapid rate. 

All the figures which illustrate this book were first en- 
graved on wood, then moulded in gutta-percha, and finally 
reproduced in copper, in the manner we have just de- 
scribed. It is with these electrotypes that the impressions 
were made, and it is the process generally employed. 

It is seen that the battery which produces this indus- 
trial deposit is one of a single cell, and that the deposit 
takes place in this single cell. 

It is impossible to imagine any more simple process ; 
but it is not as economical as it might at first appear, be- 
cause, to extract a given weight of copper from the sul- 
phate, and deposit it upon the mould, there must be con- 
sumed an equivalent weight of zinc and sulphuric acid, 
without counting the mercury lost in the manipulations. 



REMARKS UPON DANIELL BATTERIES. 137 



IRREGULARITY OF THE CHEMICAL ACTION 
m DANIELI/S BATTERIES. 

We said in the beginning that the chemical action in 
the Daniell battery was limited to the dissolving of the 
zinc, the substitution of zinc for the copper in the sul- 
phate, and the deposit of copper upon the conducting 
electrode. That is indeed the theoretical and principal ac- 
tion ; but it is not the only one. We have shown in the 
foregoing that there are local actions in the neighborhood 
of the zinc and a deposit of copper upon the zinc. 

But that is not yet all. If the Daniell battery be closely 
examined (Callaud's battery is well suited to this exami- 
nation, because one can see everything that goes on in- 
side), a continual formation of gaseous bubbles at the sur- 
face of the zinc, and indeed upon the copper electrode, 
is seen. 

As to the freeing of hydrogen from the zinc, the fol- 
lowing is the simple explanation : 

This zinc is immersed in sulphate of zinc. The zinc 
not being pure, small voltaic cells form themselves at its 
surface, and consequently the water is decomposed and 
hydrogen given off. 

The explanation is analogous concerning the coppei 
electrode; the different parts of this electrode are im- 
mersed in unequally saturated portions of the sulphate of 
copper, or even in portions containing sulphate of zinc ; 
a voltaic cell is thus constituted between the two liquids 
and the single electrode. We will return, at the end of 
this work, to identical electrode batteries, when all doubts 
the reader may here have will be dispelled. 

There is less freeing of hydrogen from the copper than 



138 TWO-LIQUID BATTERIES. 

from the zinc, no doubt because the voltaic cells formed 
have a much smaller electro-motive force. 

Whatever the truth of these explanations may be, the 
fact of the freeing of hydrogen is not to be doubted. 
Large gaseous bubbles are seen attached to the surface of 
the zinc, and in perfect stillness they may be heard to 
free themselves now and then and rise to the surface, 
making a slight noise as they explode. 

These abnormal actions are not the only ones that take 
place in the Daniell, but they are the most important. 



CHAPTEE IV. 
BATTERIES DERIVED FROM THE DANIELL. 

By replacing the copper in the Daniell battery by some 
other metal and the sulphate of copper by the sulphate 
of that metal, batteries possessing qualities analogous to 
those of the Daniell may be made. 

Several of them have a practical interest, but we will 
at first mention two that can only serve in laboratories. 

The cadmium battery -is formed of zinc, sulphate of 
zinc, sulphate of cadmium, and cadmium. Its electro- 
motive force is 0.31 ; that is, thirty-one hundredths of 
the unit, or, to use round numbers, one third of the 
Daniell battery. Such are, at least, the figures given by 
M. Jules Eegnauld. 

The aluminium battery is still more feeble : zinc, sul- 
phate of zinc, aluminic sulphate, and aluminium. The 
electro-motive force is 0.2, or one fifth of that of the 
Daniell. 

The tables at the end of this work will show other com- 
binations, which are of no interest here. 

To our knowledge, no one has ever tried the zinc, sul- 
phate of zinc, sulphate of iron, and iron battery ; a study 
of it would undoubtedly be very interesting. 

The batteries which we will now study have indeed the 
Daniell for model, but they possess a striking peculiarity; 
viz., the depolarizing salt is almost insoluble, which gives 
rise to certain interesting results. 



140 TWO-LIQUID BATTERIES. 

MAElB DAYYS SULPHATE - OF - MEECUEY 
BATTEEY. 

Of all batteries having the Daniell for model, the most 
interesting is that proposed by Marie Davy. It has been 
extensively employed, and is still used in many cases. 

Let ns substitute, in the Daniell, sulphate of mercury 
for sulphate of copper, and carbon for copper, and we 
will have the new battery. In truth, if we had strictly 
followed the model, we should have replaced the copper 
by mercury ; but the liquid nature of this metal and its 
high price have caused the preference of a carbon elec- 
trode. Besides, the action of the battery producing the 
reduction of the sulphate and the deposit of metallic 
mercury upon the negative or conducting electrode, the 
difference disappears in time, and there is in reality an 
electrode of mercury in which is immersed a piece of 
carbon. It has been proved that the electro-motive force 
is not changed by the suppression of the carbon and the 
use of mercury, provided the latter is pure. 

Fig. 34 represents the form that Marie Davy has given 
to his cell. The zinc is a hollow cylinder placed in the 
glass jar around the porous jar ; this latter contains the 
carbon electrode surrounded with a liquid paste of sul- 
phate of mercury. The carbon is capped with copper, 
to which is soldered a strip of the same metal, connected 
with the zinc of the adjoining cell. The carbon may also 
be capped with lead, and the connection made in the 
same way. In either case it is better to first dip the top 
of the carbon in a bath of paraffin, in order to fill up all 
the pores so that no liquid may rise by capillarity and at- 
tack the lead or copper. 



BATTERIES DERIVED FROM THE DANIELL. 141 

The chemical action in this battery is precisely analo- 
gous to that in the Daniell. The sulphate of mercury is 
reduced, an equivalent quantity of sulphate of zinc is 
formed, the zinc is dissolved, and metallic mercury is 
deposited in the porous jar, either upon the surface of 
the carbon-electrode or in the mass of the sulphate of 
mercury. 

In the French Telegraph, suboxide of mercury 




Fig. 34 



(S0 3 llg 2 0) is generally used ; consequently two equiva- 
lents of mercury are set free for one of zinc dissolved. 

But there are other sulphates that may also be em- 
ploye^. 

The sulphate of protoxide (HgO,SO,) is frequently 
used for medical purposes. This salt presents a singular 
peculiarity : coming in contact with water, it decomposes 
into two salts, the one basic and but very little soluble ; 



142 TWO-LIQUID BATTEKIES. 

the other acid, very soluble, which has not as yet, to our 
knowledge, been analyzed. The first salt has a yellow ap- 
pearance, whose formula is 3(HgO) S0 3 ; it is therefore 
a tribasic salt. 

Marie Davy's batteries may be charged with mono- 
basic sulphate of protoxide (HgOS0 3 ), and even with 
the tribasic sulphate alone [3 (HgO) S0 3 ], and we are as- 
sured that these two batteries have sensibly the same 
electro-motive force as that in which sulphate of suboxide 
(Hg 2 OS0 8 ) is used. 

It is said that this last salt ought to be preferred to 
the others, because the tribasic salt, mentioned above, 
breaks the porous jars by its little solubility ; but admit- 
ting this, the two salts of protoxide can very well be used 
in gravity batteries, of which we shall speak further on. 

Marie Davy's battery presents the following advan- 
tages : 

1. It has an electro-motive force very much superior to 
that of Daniell ; it is represented by 1.5. 

2. The slight solubility of the sulphate of mercury 
causes but a very slow diffusion in the outer liquid ; the 
result is that the local actions and the waste are not so 
important as in the Daniell battery. 

3. The mercury which is deposited upon the zinc hy 
local action, and without any corresponding production of 
electricity, amalgamates the zinc, or keeps up its amalga- 
mation, which is very useful and prevents the waste of 
the sulphuric acid if it is used in the outside jar. 

The faults of this battery are as follows : 
The sulphate of mercury is a violent poison ; the price 
of this salt is high and very variable, as the price of the 
mercury itself. Finally, it is apt to weaken under certain 
circumstances, as we will show in detail. 



BATTERIES DERIVED FROM THE DANIELL. 143 



WEAKENING OF THE SULPHATE -OF - 
MERCURY BATTERY. 

When Marie Davy's battery is employed for the tele- 
graph or any intermittent service, no variation in the 
electro-motive force is noticed, and the battery may be 

regarded as constant. But if the circuit remain continu- 
ed 

ously closed, or if the intervals of its being open are too 
short, a diminution in the intensity is observed. This 
diminution is the result of several causes. We will com- 
mence by speaking of one of them, which we have not 
yet met in the course of this study. 

The. special characteristic of the Marie Davy battery, 
when compared with the Daniell, is the insolubility of the 
mercurial salt. It must, however, be noted that the sul- 
phate of mercury is not altogether insoluble, but very 
little soluble, and it would be a great mistake to call the 
battery which we are now studying a single liquid bat- 
tery. There are, in reality, two liquids, the solution of 
sulphate of zinc and that of sulphate of mercury. In 
1860 we made the following experiment : 

A solution of sulphate of mercury was prepared and 
well filtered, so that no traces of undissolved salt might 
remain ; then a battery charged with zinc, sulphate of 
zinc dissolved, sulphate of mercury dissolved, and carbon. 
This battery had exactly the same electro-motive force as 
that of an ordinary Marie Davy battery containing 100 
grammes (or more) of paste of mercurial salt. 

The comparison was made by opposition with a very 
sensitive galvanometer ; there was, therefore, no room for 
any doubt. 

But if this filtered solution of sulphate of mercury 



144 TWO-LIQUID BATTERIES. 

battery were called upon to furnish a current, it would be 
seen to weaken very rapidly, which is easily under- 
stood. 

The very small quantity of mercurial salt dissolved was 
soon exhausted, and depolarization was no longer effected ; 
from that moment it was simply a single-liquid battery 
which polarized promptly. 

That is, in reality, what may be expected in all batter- 
ies containing an only slightly soluble depolarizing salt, 
when they furnish a large quantity of electricity. If the 
consumption of the dissolved mercurial salt is more rapid 
than the dissolving of the salt in the liquid, the solution 
of course weakens, and finally does not act at all, so that 
the battery is no longer a two-liquid battery but a single- 
liquid one, and consequently becomes weakened by polar- 
ization. 

The above constitutes the first period of the action of 
the battery. We will now examine the second. As soon 
as the battery is reduced to a single liquid it becomes sub- 
ject to polarization. This polarization is subject to the 
rules that we have indicated in the first part of this work. 
It depends upon the intensity of the current, and assumes 
a much greater value when the cell in question is polar- 
ized by the current furnished by other cells joined with 
it in intensity. It depends upon the dimensions of the 
cell and of the elements. And it depends, finally, upon 
the length of time of the experiment and upon the resist- 
ance of the circuit. 

This is the same phenomenon that we have already 
studied several times. But a third period has been ob- 
served in this battery, and also in others. When a cell 
becomes extremely polarized it loses all its force, and then 
electrolysis of the sulphate of zinc takes place. This salt 



BATTEEIES DEBITED FROM THE DANIELL. 145 

is decomposed, zinc is deposited upon the carbon, and, 
coming in contact with the mercury there, the two unite 
and form one amalgam of zinc, which is at first positive, 
but which soon becomes negative, as compared with the 
zinc, when the quantity dissolved in the mercury becomes 
considerable. Thus is formed a zinc amalgam-of-zinc 
cell whose poles are contrary to those of the original cell, 
in other words, the poles are reversed in this third period. 
We have previously pointed out an analogous action as 
taking place in the salt-water battery, and it is probable 
that the cause is the same. Now this reversing of the 
poles and the extreme polarizations do not take place in 
the general operations of the telegraph, because the cells 
are only used intermittingly and have time, during the 
intervals of repose, to depolarize. 

It is understood that the smaller the cells and the less 
mercurial salt they contain, the more rapid the weakening 
of the solution of sulphate of mercury. Therefore cells 
4f inches high are recommended. Cells of these dimen- 
sions, however, cost a great deal, and in general cells 3-%\ 
inches high are adopted, which are all that is necessary for 
unimportant telegraph offices. 

Care should be taken that the level of the liquids re- 
main sensibly the same in cells joined in intensity, be- 
cause if in one the level is notably lowered, it is as if this 
cell had become smaller ; the dissolved mercurial salt of 
this cell would become rapidly exhausted and the cell 
would polarize. 



146 



TWO-LIQUID BAJTEEIES. 



SULPHATE -OF -MERCURY GRAVITY BAT- 
TERY. 

A French physicist arranged snlphate-of -mercury cells 
after the model of Callaud's battery, and succeeded very 
well by adding to the mass of mercurial salt fragments of 
crushed gas-retort carbon (volume for volume). This car- 




Fig. 35. 



bon produces a kind of drainage and prevents the salt 
from becoming too compact, which in ordinary batteries 
renders the dissolution slower than is proper. 



BATTERIES DERIVED FROM THE DANIELL. 147 

We believe that the tribasic salt of sulphate of protox- 
ide of mercury, which is less costly than the other mer- 
curial sulphates, might well be employed in batteries of 
this kind. 

TROUVfi'S REVERSIBLE BATTERY. 

Trouve arranged, with a view to medical purposes, a 
battery which presents incontestable advantages for cer- 
tain uses. 

A cell of this battery is shown in Fig. 35. The out- 
side jar is a cylinder of ebonite, closed at both extremi- 
ties by ebonite screw tops. At the upper part is seen 
the zinc in the shape of a small cylinder fixed in the 
middle, to which is attached a wire that passes through 
the top and constitutes the. negative connection of the 
cell. The carbon is cylindrical and surrounds the zinc. 
The liquid, formed of water and of sulphate of protoxide 
of mercury (S0 3 HgO), does not reach the lower part of 
the zinc, when the cell is placed, as shown in the figure ; 
but if it be turned upside down or put upon its side, the 
liquid comes in contact with the electrodes and the cur- 
rent begins to flow. 

The cell is hermetically closed, and there is no danger 
of any leakage. It is very convenient for many purposes, 
and forms part of some Volta-induction apparatus made 
by Trouve. 

GAIFFE'S BATTERY. 

Gaiff e uses the sulphate of mercury battery for his 
Voltaic-induction apparatus. Two cells are joined, as 
Fig. 36 shows. Each cell is contained in a small sepa- 
rate vessel of ebonite, at the bottom of which is a carbon 



148 TWO-LIQUID BATTEKIES. 

plate. Upon the carbon is placed some water and sul- 
phate of protoxide of mercury. A small plate of amal- 
gamated zinc is immersed in this liquid, and is furnished 
with a little knob in the centre by which it may be lifted 
out. The zinc rests upon platinum wires fastened in the 




moulding of the ebonite, which establish the communica- 
tion with the carbon of the adjoining cell. 

These batteries may work for about an hour, when the 
sulphate should be removed. This liquid is generally 
freshly made every time the induction apparatus is used, 
and the old water and yellow sulphate are thrown away. 

LATIMER CLARK'S STANDARD BATTERY. 

This eminent electrician proposed to " discover a form 
of the Voltaic battery having a perfectly constant elec- 
tro-motive force and maintaining an invariable difference 
of potential between its poles." * 

He has found that the voltaic combination which best 
fills these conditions is an element composed of zinc, sul- 
phate of zinc, sulphate of mercury, and mercury. 

The zinc ought to be chemically pure :_ distilled zinc is 
used. 

The formula for the sulphate of mercury is Hg 2 OS0 3 ; 
it is a white salt that does not become yellow by the ad- 

* Philosophical Transactions of the Royal Society, June 19, 1875. 



BATTERIES DERIVED FROM THE DANIELL. 149 

dition of water. It is prepared by dissolving pure mer- 
cury in warm sulphuric acid, but not boiling ; it must be 
carefully washed, because the presence of any free acid 
would notably change the results. The salt must con- 
tain no sulphate HgOS0 3 (sulphate of protoxide), recog- 
nized by its transformation into a yellow salt by the action 
of water. 

The sulphate of zinc should be pure and used in a 
state of saturation ; it can be easily understood that its 
composition can thus be rendered more constant. 

The battery is prepared as follows : The sulphate of 
zinc is dissolved in distilled boiling water, left to cool, 
gently poured off, and the saturated liquor thus obtained 
is used to form a thick paste with sulphate of mercury ; 
Uiis paste is heated to 100° centig. in order to expel any 
air it may contain. It is then poured upon the previously 
heated surface of the mercury, the zinc is suspended in 
the paste, and finally the jar is closed with melted paraffin. 

The positive connection is a platinum wire passing 
through a glass tube and descending to the mercury. A 
better plan is to place this positive connection in an out- 
side glass tube which opens into the jar near the bottom. 

" The electro-motive force of these elements is remark- 
ably constant, provided they remain open and be not 
weakened by work. Numerous experiments have been 
made between new ones and others which had been used 
several months, and it was found that the greatest dif- 
ferences did not reach one thousandth part of the total 
value of the force." 

Experiments have been made to determine the varia- 
tions in the electro-motive force with the temperature. 
The average showed a diminution for an increase of tem- 
perature in the proportion of six hundredths per degree 



150 TWO-LIQUID BATTERIES. 

centigrade. The variations are more marked as the ther- 
mometer nears 0° centig., about eight hundredths per de- 
gree ; from 5° to 25° they are about .06 per cent, and 
about .055 per cent up to 100° centig. 

Mr. Clark has determined the electro-motive force in 
absolute measurement, and has found it to be 1.4573 
volts, and 1.4562 volts with a sine galvanometer, the tem- 
perature being 15.5° centig. 

SULPHATE -OF -LEAD BATTEEY. 

This is the same kind of battery as the sulphate-of- 
mercury battery. It is a Daniell with an almost insolu- 
ble depolarizing salt ; it is formed of zinc, sulphate of 
zinc, sulphate of lead, and lead. 

The cheapness of sulphate of lead has caused this bat- 
tery to be extensively used, but it has finally been aban- 
doned for certain reasons, which we will give farther on. 

M. Becquerel was the first to try this combination. 
His conducting electrode was either lead or a piece of 
carbon, a piece of copper or tin. 

In 1860 Marie Davy proposed a new form which has 
been abandoned ; it deserves notice, however, as it was a 
good imitation of Yolta's column battery, and has been 
imitated in turn by Sir William Thomson in his large 
Daniell gravity battery. 

Marie Davy's elements consisted of pans of tinned iron 
provided with three arms placed horizontally and at equal 
distances apart. L T pon the under side of each pan was 
soldered a disc of zinc covering the whole bottom. In 
each pan was a layer of sulphate of lead about •§- of an 
inch thick and a portion of pure water or water con- 
taining a little sulphate of zinc. The pans are placed 



BATTERIES DERIVED EROM THE DANIELL. 151 

one above the other, so that the zinc of one is immersed 
in the liquid of the other below it. It is necessary to 
keep the successive cells at equal distances apart, which is 
done by means of vertical wooden supports to which the 
horizontal arms are fastened. A battery of forty cells of 
this kind forms a column about 40 inches high. This 
form, however, has not been preserved ; it weakened 
rapidly, and we believe that its principal defect lay in the 
too small quantity of water it contained. 

M. Edmond Becquerel gave to the sulphate-of-lead 
battery the regular form of porous jar-cells. He ar- 
ranged a solid cylindrical mass of sulphate of lead around 
a central piece of lead from ^ to J of an inch in diame- 
ter. Consistency may be given to this mass by mixing it 
with chloride of sodium (100 grammes of dried and 
crushed sulphate of lead and 20 grammes of sea-salt), 
and by wetting it with a saturated solution of sea-salt (50 
cubic centimetres). This cylindrical mass of sulphate of 
lead may be surrounded by a layer of plaster, which serves 
as a porous jar. 

Finally, ordinary porous jars may be used containing 
the lead and the sulphate. 

One of the faults in this battery is that its electro- 
motive force is about one half that of a Daniell, while its 
resistance is very great. The result is that, in order to 
obtain the same intensity, a number of cells more than 
double that of the Daniell battery is required. It would 
seem, from the foregoing, that this battery would be 
badly adapted to an electric-bell service, as the bells are 
placed in circuits of little resistance, and their electro- 
magnets themselves have but little resistance ; therefore 
the internal resistance of the battery is greater than that 
of the outside circuit, which is a very unfavorable con- 



152 TWO-LIQUID BATTERIES. 

dition. It is, however, to this use that the battery in 
question has been put, and it must be that it does all that 
is required of it. 

It would seem that the economy resulting from the use 
of a cheap salt would be more than balanced by the 
necessary number of cells, and by the cost of so much 
zinc and so many glass and porous jars. This considera- 
tion must have finally attracted attention ; for sulphate- 
of-lead batteries have been gradually abandoned. 

WEAKENING OF THE SULPHATE OF LEAD 
BATTERY. 

There happens in the battery in question precisely 
what we have seen in Marie Davy's battery : the sulphate 
of lead does not act unless dissolved. This dissolution is 
slow, and if the consumption of electricity is active, and 
consequently that of the dissolved sulphate of lead, the 
solution weakens and the battery ceases to be depolarized ; 
in other words, the battery becomes weakened. 

It is probable that if an energetic current were made 
to act upon the battery thus polarized, the sulphate of 
zinc would be electrolyzed and zinc would be deposited 
upon the lead, as in Marie Davy's cell. This observation 
has no practical interest, but only tends to show once 
more the great similarity of the sulphate-of-lead battery 
to the mercurial-salt battery. 

If the sulphate-of-lead battery were again to be used, 
we believe that there would be an advantage in putting 
pieces of gas-retort carbon in the mass of sulphate of lead ; 
this would facilitate the dissolving of that salt which is 
the condition of depolarization, and it would also give a 
greater conductivity to the mass which fills the porous jar. 



BATTERIES DERIVED FROM THE DANIELL. 153 



VARIOUS SALT BATTERIES. 

By substituting for the sulphate of copper and zinc in 
the Daniell the corresponding nitrates, or the acetates, 
or the chlorides, simple modifications of the Daniell are 
obtained. None of these batteries have any practical in- 
terest, on account of the high price of the materials. 

M. Jules Regnauld has carefully measured the electro- 
motive forces of several of these batteries, and the com- 
parison of the figures is worthy of attention. 

Pure Zinc Copper. Electro-motive force 

expressed in Volts. 

Sulphate of zinc -.Sulphate of copper 0.955 

Nitrate " '.' Nitrate " " 0.873 

Acetate " " Acetate " " 0.955 

Chloride " " Chloride " " 0.955 

The equality of these figures is very interesting. But 
from these particular instances no law of physics can be 
deduced : other measurements of M. Regnauld show that 
this equality does not exist in all analogous series of bat- 
teries. 



OHAPTEE V. 

ACID BATTERIES. 

In the beginning of Part II. of this work we indi- 
cated how the electrode may be depolarized by means of 
substances rich in oxygen and easily decomposed, notably 
highly oxygenated acids. The experiment which we 
then cited is due to Grove, and has led to the production 
of one of the best batteries known. 

GKOVE'S BATTEKY. 

To remain faithful to our method of exposition, we 
should consider Grove's battery as one of the derivatives 
of Volta's. In the latter the zinc is attacked by the di- 
lute suphuric acid, and hydrogen is evolved upon the con- 
ducting electrode, copper, platinum, or carbon. If this 
platinum electrode be surrounded by nitric acid, the latter 
is decomposed, oxygen is set free and forms water with 
the polarizing hydrogen, and nitric oxide is given off. 
The battery thus modified is without polarization, or, in 
other words, is constant. It is known by the name of 
Grove's battery, and dates from the year 1839. 

That which is commonly called Grove's battery con- 
tains a conducting electrode of platinum ; it is under- 
stood, however, that Grove's conception is a general one 
and may be easily modified. Fig. 37 represents this 
battery under its most common form. 

A square porcelain jar is used as the outside recipient ; 



ACID BATTEEIES. 



155 



it contains a well-amalgamated zinc electrode, having the 
shape of an U. Inside of the zinc thus shaped is placed 
a porous jar containing a very thin piece of platinum, 
which serves as the conducting electrode ; water acidu- 
lated with sulphuric acid is put with the zinc in the out- 
side jar, and nitric acid fuming is poured in the porous 
jar. The platinum is connected, as shown in the figure, 
with the projecting portion of the zinc in the adjoining 
cell. 

Such is the form of Grove's cell employed in England 




Fig. 37. 

to the entire exclusion of Bunsen's form, so generally used 
in France. We will speak of the latter farther on. 

In Germany, Poggendorfs arrangement of Grove's 
cell is used. The porous jar is cylindrical and contains 
the platinum in the shape of an S, in order to offer as 
large a surface as possible. The platinum is fastened to 
a porcelain stopper which almost completely closes the 
porous jar. This arrangement is represented by Figs. 38 
and 38a. We will not dwell any longer upon it, because 
we believe that Grove's battery has received but a limited 



156 



TWO-LIQUID BATTEEIES. 



application in Germany, and that Bunsen's disposition is 
generally preferred. 

Our main object is more to make known those batteries 
which, in one country or another, are the most exten- 




Fig. 38. 




sively employed, and not so much to treat of the many 
combinations which are only theoretically interesting. 



CHEMICAL ACTIONS IN GKOVE'S BATTEEY. 

"We have said that the zinc becomes oxidized at the ex- 
pense of the water and form's sulphate of zinc ; that the 
hydrogen of the water thus decomposed reduces nitric 
anhydride (N 2 5 ) and produces nitric oxide (NO). 
This latter gas, coming in contact with the air, is trans- 
formed into nitric tetroxide, recognizable by its color and 
by its suffocating properties. It is absolutely certain that 
the Grove batteries produce nitric tetroxide ; therefore 



ACID BATTERIES. 157 

the decomposition of nitric acid must surely produce ni- 
tric oxide, as we said above ; but that this is the only form 
of decomposition that takes place is not certain. On the 
contrary, it is probable that nitric trioxide is produced. 
This appears to be the result of theoretical considerations, 
into the details of which we cannot enter.*" 

Other actions take place in Grove's cell, one of which 
is the formation of ammonia. If, in fact, after the liquids 
are exhausted they be evaporated, it is observed that the 
addition of lime in the concentrated liquid produces an 
abundant freeing of ammoniacal gas. This proves that if 
a portion of the hydrogen has combined with the oxygen 
of the nitric acid to form water, another portion has com- 
bined with the nitrogen to form ammonia.f 

Unfortunately batteries have not been completely ex- 
amined from a chemical point of view, and it is not 
known precisely what takes place within them. To com- 
pletely elucidate the question, the gases evolved in each 
cell should be separately collected ; then these gases and 
also the matter left in the liquids should be analyzed. 



PKACTICAL DETAILS. 

The platinum electrodes are generally 5 in. high by 
2 in. wide, and they must not be too thin, for the resist- 
ance would thus be increased in a manner extremely det- 
rimental to the desired results. 

There is no serious disadvantage in permitting the 
porous jar to touch the zinc, and on the other hand it is 
very important to diminish as much as possible the dis- 

* See Daniell, " Introduction to Chemical Philosophy." 
\ See Gavarret, "Traite d'Electricite, " t. ii. p. 446. 



158 TWO-LIQUID BATTERIES.. 

tance between the electrodes and consequently the resist- 
ance of the cells. 

The U form of the zinc is not very economical, because 
it breaks at the bottom before it is worn at the top. It 
has been proposed to place some mercury in the bottom 
of the porcelain jar and to use two zinc plates, one on 
each side of the porous jar, which are thus united by the 
mercury at the bottom. This disposition, which we have 
already indicated for other batteries, allows the more com- 
plete consumption of the zinc. 

« BUNSEJSPS BATTEEY. 

In the beginning, Grove thought of substituting char- 
coal or even gas-retort carbon for the platinum, and sev- 
eral public experiments were made in London ; these, 
however, had been forgotten when, in 1843, Bunsen be- 
came possessed of the same idea and succeeded in intro- 
ducing the general use of his arrangement. 

Without further insisting upon the history of this in- 
vention, we will first describe Bunsen's battery as it is 
used in France, and then the form employed in Germany, 
which is very like that originally proposed by Bunsen. 

FBENCH MODEL (Fig. 39.) 

The outside jar is made of glazed earthenware, which 
is less fragile than glass, and this consideration is impor- 
tant in the use of a battery which is often moved from 
one place to another at greater or less distances. For bat- 
teries which always remain in the same place there is no 
inconvenience in the use of glass jars ; but as their cost 
is very little less than that of the glazed earthenware 



ACID BATTERIES. 



159 



jars, the latter are nearly always used, at least in France. 
Earthenware subject to fracture should be avoided, for 
the acid enters into the cracks of the enamel, rendering 
the jar permeable and fragile. 

The zinc is formed of a plate of zinc ^ of an inch 
thick, rolled in the shape of a cylinder and well amalga- 
mated, which latter precaution allows the zinc to be left 




Fig. 39. 

twenty-four hours in acidulated water without its being 
sensibly dissolved. 

Some persons solder to the zinc a strip of copper which 
constitutes the negative connection of the cell; but the 
two must be riveted together -by means of a copper rivet, 
otherwise the mercury will finally detach one from the 
other. These means of connection are, however, not to 
be recommended. The zinc should be higher than the 



160 TWO-LIQUID BATTERIES, 

earthenware jar and should be furnished with a binding 
screw, to which the positive connection of the adjoining 
cell is attached. This arrangement has the following ad- 
vantages : 

1. Every time the battery is charged, that part of the 
binding screw which comes in contact with the zinc (and 
that part alone) should be cleaned with emery-paper. 
This is very quickly done, and assures to the operator a 
good contact at those points through which the current 
passes. 

2. When, after having used the battery a certain num- 
ber of times, the zinc becomes worn at the bottom, it may 
be turned upside down. Thus the zinc is used up more 
completely and regularly before it becomes necessary to 
renew it. 

3. The zinc, thus reduced to- a simple cylinder having 
no piece of any kind attached to it is easily packed and 
requires but a small box for transportation. 

The porous jar is placed in the centre of the zinc cylin- 
der and has about the same height. It should be very 
porous and permit an easy communication of the liquids 
it separates. 

The negative electrode has the shape of a prism with a 
rectangular base ; it should reach above the porous jar, 
in order to facilitate the connection. We have explained 
the advantages of the binding screw, and we here repeat 
that every time the battery is recharged the parts of the 
binding screw which touch the carbon should be cleaned 
with emery-paper, in order to secure a perfect contact. 

Before the invention of the binding screws, various 
more or less imperfect means were employed for the con- 
nection with the carbon. A conical copper cork was 
forced into a hole made in the top of the carbon ; or cop- 



ACID BATTERIES. 161 

per was deposited upon the head of the carbon, to which 
a strip of copper was then soldered. Other means, some 
of which we have already pointed out, were also em- 
ployed. 

All of them presented inconveniences more or less 
marked, and we do not hesitate to say that they should 
all be discarded, and the binding screws exclusively 
adopted. These latter have been used for many years by 
those persons who successfully produce electric light by 
means of batteries. We insist upon this recommendation, 
because a single imperfect contact suffices to cause a no- 
table loss of energy in a battery of fifty or sixty cells. 

AMALGAMATION OF THE ZINC. 

We have said above that it is necessary to amalgamate 
the zinc. If this precaution be neglected when the zincs 
are used with concentrated acids, gases are evolved charged 
with acid vapors, which render the care of the battery 
troublesome and which are injurious to the health. 

We have also said that by amalgamation the zinc is 
made more electro-positive, and that consequently the 
electro-motive force of the cells is increased (an inspection 
of the tables at the end of this work will make this very 
plain). 

It is therefore necessary that this operation be made 
with great care, and the simple and regular form of the 
zinc described above renders the process comparatively 



In order to thoroughly amalgamate the zinc, it should 
first be well scraped and cleaned. The following is the 
process which we recommend : 

The zincs are placed on end in a bucket of water 



162 TWO-LIQUID BATTEKIES: 

containing one tenth of sulphuric acid. They stand out 
of the liquid about half an inch, so that they may be lifted 
out without immersing one's fingers in the acid. Three 
zincs are placed at one time in the bucket, in order that 
each one may remain in the cleansing solution the length 
of time required for the amalgamation of the other two. 
A rotation is established in the following manner : Every 
time that one zinc is taken out to be amalgamated it is 
replaced by a new one, so that there may be always three 
in the cleansing solution. The other two have in the 
mean time been turned upside down, in order to immerse 
the parts which were exposed to the air. 

The vessel containing the mercury for amalgamation 
has the shape of a portion of a cylinder ; it is a' little 
longer than the zincs to be amalgamated. This is the 
most rational form, for it permits the use of the smallest 
quantity of mercury. The zincs are carefully immersed 
in the mercury, the longitudinal opening downwards, in 
order that the mercury may the more easily reach the in- 
terior of the cylinder. The zincs are then turned slowly 
once or twice, to insure the amalgamation of the entire 
surface. At the moment of taking the zinc out of the 
mercury it should be held at an angle of ten or twelve 
degrees to allow the superfluous mercury to run off. It 
is then lifted out in a horizontal position with the longi- 
tudinal opening upwards, so that no drops of mercury 
may rjln off at the angles and thus be lost. 

The zincs are finally placed in an empty tub or trough 
capable of containing several of them ; after a certain time 
a quantity of mercury is found at the bottom, having run 
off from each zinc. 

The vessel used for amalgamation is of enamelled cast- 
iron, thus being 1 most solid and unalterable. 



ACID BATTERIES. J 63 

The zincs ought to be amalgamated but a few hours be- 
fore the battery is charged, and they ought to be re- 
amalgamated every time the battery is used, even if there 
be only twelve hours' interval. 

The cleaning requires a little longer time when the 
zinc is new, and above all when it is covered with layers 
of adhering salts which remain from preceding operations. 

TO MOUNT THE BATTERY. 

This operation requires a good deal of method for a 
battery of fifty or sixty cells, such as is used for electric- 
light purposes. 

The earthenware jars should be placed at short distances 
from each other, so that they do not touch ; they should 
be placed in one row or in two, or, if room permits, in a 
circle. The object of these arrangements is to facilitate 
the filling and emptying of the cells. Place the cells, if 
possible, upon a table covered with squares of porcelain as 
are frequently found in laboratories, or, still better, upon 
rods of glass. In the absence of the above conveniences, 
the jars may be ranged upon planks of dry wood, but if 
possible avoid placing them upon the ground in the open 
air. It can be easily understood that there is an advan- 
tage in suppressing all losses or irregular communications 
between the cells, such as are occasioned if the jars are 
damp, or if thev sre placed upon clamp earth, or if they 
touch each other.. A striking proof of the existence and 
importance of these losses is shown in the following phe- 
nomenon, which takes place every time the above precau- 
tions for insulating are neglected : Whenever one touches 
any one of the poles of the battery, a shock is felt which 
is caused by the currents passing into the earth.' 



164 TWO-LIQUID BATTERIES. 

The cause of these communications is the formation 
(upon the surfaces of the jars and supports) of steam and 
acid vapors, which are abundantly freed from the cells 
as much by their high temperature as by the chemical 
action. 

As soon as the earthenware jars are arranged, the 
zincs, the porous jars, and the carbons are put in, the 
latter being first furnished with their respective binding 
screws. The connections are then made between the 
cells, so as to form a kind of chain, commencing with the 
carbon (positive pole of the battery) and ending with the 
zinc (negative pole of the battery). 

"Whether the cells be arranged in rows or in a circle, 
the screws and connections should be placed so as to be 
in the operator's way as little as possible when he is 
pouring in the liquids. 

The battery may be thus mounted, without any incon- 
venience, several hours before using it, since it contains 
no liquids. 

TO CIIAKGE THE BATTERY. 

If the porous jars are new there is an advantage in 
charging the cells one or two hours before using the 
battery, so that the liquids may have time to penetrate 
the porous jars. 

If, on the other hand, the porous jars have . already 
served, they have retained liquid acids in their pores, and 
it suffices to charge the battery half an hour or even 
quarter of an hour before working it,, especially if the 
battery is to work more than three or four hours. 

It is important that the cells be charged in the shortest 
time possible, in order that those first charged may not 



ACID BATTERIES. 165 

be in notably different conditions from the last ones ; 
therefore preparations should be made in advance, and 
the quickest means employed for pouring in the liquids. 
Acidulated water should be prepared in a large tub, in 
order that all the jars may contain the same liquid. 
Thirty-three jars of pure water (the size of those used in 
the battery) and three jars of sulphuric acid, at 66° 
centigrade, are poured into the tub. The water is put 
in first, and then the sulphuric acid is slowly added, 
being stirred all the time, in order to render the mixture 
as homogeneous as possible. This mixture becomes 
greatly heated, as is known, and if the temperature 
becomes too high the pouring of the acid should be 
stopped, and the liquid in the tub agitated with a stick 
of wood or a rod of glass, or even with one of the amal- 
gamated zincs of the battery. 

This mixture can very well be prepared several hours 
in advance ; there is no inconvenience occasioned, how- 
ever, in using it before it cools off — there is rather an 
advantage. The only important point is that it be per- 
fectly homogeneous, or, in other words, well mixed. 

The liquid is generally drawn from the tub in a 
pitcher and poured into a funnel held in the hand over 
the jars ; this is, however, very fatiguing for the operator, 
and necessitates strict attention, in order that the liquid 
may be at the same level in all the jars. We recommend, 
therefore, the use of a rubber siphon, like that used in 
charging the Callaud battery. At one end of the rubber 
tube is a piece of glass or ebonite, flattened to facilitate 
its insertion in the jars between the zinc and porous jar. 
At the other end there is an ebonite mouthpiece, furnished 
with lead, in order that it may descend to the bottom of 
the reservoir containing the liquids used to fill the jars. 



166 TWO-LIQUID BATTERIES. 

In order that it may not run too slowly, the reservoir 
should be placed a metre higher than the jars to be 
filled. The end of the tube is held in the hand, and it is 
only necessary to press it with the fingers in order to stop 
the flowing. This system dispenses with a spigot, produces 
an instantaneous stop, and allows the regulation, within a 
fraction of an inch, of the level of the liquids in the cells. 

The liquid is started in the siphon in the following 
manner : 

In the hand are held the two extremities of the tube, 
which hangs below. Water is poured in until it appears 
at both extremities, then the mouthpiece is quickly placed 
in the reservoir of acidulated water and a certain quantity 
of liquid is allowed to run off, in order to purge the tube 
of the pure water it contains: From that time on every- 
thing is ready for the filling of the jars. 

This operation terminated, the tube should be well 
rinsed with water- containing a little ammonia, by which, 
precaution it may be made to serve* a long time. 

For the pouring of the nitric acid a funnel or bottle 
or any vessel having a spout may be used. 

The siphon may also be used, but we recommend 
"Wigner's manner of starting the nitric acid in the siphon ; 
which is done as follows : 

The quantity of liquid being smaller, it may be put in 
a flask whose stopper is fitted with two tubes, one going 
to the bottom of the liquid and the other not quite 
reaching to the level of the liquid. By blowing in this 
second tube the liquid is forced into the siphon, by means 
of which one person may charge fifty or sixty cells in 
twenty or twenty-five minutes. 

A very neat invention of Mr. Lufbery, for the emp- 
tying of casks, flasks, etc., etc. is shown in Fig. 39$. 



ACID BATTERIES. 



167 



The special stopper, represented apart to the right in the 
cut, is conical and hollow, and can he adjusted in the 
month of any bottle or flask. This stopper is fitted with 
an emptying tube, A, and a tube, B ; by blowing in the 




Fig. 39a. 



latter the liquid is started in the former. The spigot at 
the end of the tube A, represented to the left in the cut, 
is kept closed by a rubber band. It is opened by pressing 
the upper part between the fingers. 



168 TWO-LIQUID BATTERIES. 

Analogous arrangements are employed in all labora- 
tories for the charging of batteries, and are considered 
indispensable. 

TO DISMOUNT THE BATTEEY. 

It is plain that as soon as the battery is no longer 
used, there is an advantage in stopping the waste of the 
zincs and the acids, which is done by taking the battery 
to pieces. 

It is necessary to have a well-determined method for 
this operation, which frequently has to be done late at 
night and with a very poor light. Everything must be 
done in advance. The zincs and the binding screws are 
placed in a tub of clear water ; if there is time the zincs 
may be taken out of the water to drip, but there is no 
disadvantage in allowing them to pass the night in the 
water. 

The carbons must then be taken out and carefully 
ranged in special earthenware vessels. It is better not to 
put them in water at first, but to allow them to imbibe 
acids, which will improve them for the future. 

The contents of the porous jars should then be emptied, 
by means of a funnel, into the vessel destined to contain 
the acid. This is the most difficult part of the work 
because of the very abundant vapors given off, which 
occasion a violent cough if proper precautions are not 
taken for keeping at a distance. 

It is almost impossible to preserve and again use the 
water acidulated with sulphuric acid, and it may remain 
all night or longer in the jars without causing any incon- 
venience. 

The nitric acid may be again used if the battery has 



ACID BATTERIES. 169 

not worked more than about three hours. By mixing it 
with some fresh acid, it may be used in the same battery 
and for the same length of time. The best plan, how- 
ever, is to sell it to certain branches of trade where old as 
well as new acids may be employed. 

Finally, the acidulated water is thrown out and the jars 
completely emptied ; the zincs are dried, after having 
been left a certain length of time to drip ; the binding 
screws are dried by being put in a box of sawdust, and 
finally all the vessels used are emptied and cleaned. 

Unless one has been in the habit of performing this 
long operation, he is very likely to burn his fingers with 
the acids ; therefore the use of rubber gloves during the 
work is recommended.' 

It is a good plan also to have within reach a little am- 
monia, into which the fingers may be immersed in case 
of any accidents, or which may be put upon any spot made 
on the clothes by the acid. 

It is seen that the use of a large Bunsen or Grove bat- 
tery necessitates a long and tedious piece of work, espe- 
cially if done in a new place ; the work is much less, of 
course, in a laboratory where one has everything at hand 
and where the operation has been performed more than 
once. 

If the battery is thus taken to pieces in a room, there 
must be some sort of an arrangement for rapidly carry- 
ing off the acid vapors ; otherwise it would be impossi- 
ble to finish the work or even to enter the room. 

Some employ a breathing apparatus like that of M. 
Gallibert, with which one may remain in a place filled 
with a dangerous gas without any inconvenience. 

In order that the zincs may be well preserved during 
the long intervals between experiments, they should be 



170 TWO-LIQUID BATTEEIES. 

carefully dried and placed on end one above another, and 
only coming in contact at several points. As for the 
porous jars and the carbons, there is, as we have said, no 
advantage in rinsing them ; it is indeed better to allow 
them to imbibe the acids of the battery, which gives them 
a more immediate conductivity in making future experi- 
ments. 

COMPOSITION OF THE LIQUIDS. 

We have said that, in general, dilute sulphuric acid is 
put with the zinc and nitric acid with the carbon ; but 
each experimentalist has his own liquid, and some of these 
compositions deserve attention. 

We have stated in Part I., that a solution of sulphu- 
ric acid having a density of 1.25, and composed of 30 
parts of monohydrate acid for 70 parts of water, pos- 
sessed the greatest conductivity, and that it is never used 
because too dangerous. In general, liquids containing 
eight or twelve parts, by weight, of sulphuric acid for a 
hundred of the mixture are used, whose conductivity dif- 
fers but little from the maximum. In the practice, 
weights being more difficult to establish than volumes, 
the following mixtures are used : one volume of acid for 
six of water, or three volumes of acid at 66 hydrometric 
degrees for thirty-three of water. 

The electro-motive force decreases (the resistance at 
the same time increasing) when the proportion of water is 
increased after the liquid has attained the density 1.25, as 
is shown in Table YIII. by the experiments of Paggendorf. 

Generally, nitric acid at 40 hydrometric degrees is em- 
ployed in the porous jars ; the electro-motive force di- 
minishes notably with the density of the -nitric acid. 



ACID BATTERIES. 



171 



Sonic persons, and especially "Wigner, replace tlie nitric 
acid by a mixture of two parts by weight of nitric acid 
(specific gravity 1.360) and five of sulphuric acid (speci- 
fic gravity 1.845). The proportion of nitric acid is sonic- 
times increased to three and a half parts, if the battery is 
to work more than four or five hours. 

It is true that "Wigner's experiments were made with 
the Grove battery, which is only employed in England, 




Fig. 40.' 

but it appears certain that the same results might be ob- 
tained from carbon batteries. 

There is a very evident economy in the use of Wig- 
ner's mixture, as sulphuric acid costs much less than nitric 
acid. 

In 1853 a French physicist studied this question and 
discovered that there was a considerable economy in sub- 
stituting for the nitric acid in the Bunsen battery a con- 
centrated solution of sulphuric acid to which was added 



172 



TWO-LIQUID BATTEKIES. 



one or two twentieths of nitric acid. Sulphuric acid evi- 
dently acts as an absorbent of water, and renders the de- 
composition of nitric acid much more effectual than when 
the latter is in a large quantity of water. 

As sulphuric acid can absorb the water of its bulk in 
nitric acid, which is successively added in the jar, one 
may almost completely use up a given quantity of nitric 
acid, which, if used alone, would have to be thrown away 
long before it had become exhausted. 

GEKMAN MODEL. 

In the beginning Bunsen placed the carbon in the out- 
side jar and gave it the form of a hollow cylinder, in the 
centre of which was placed the porous jar. The porous 
jar contained the amalgamated zinc with acidulated water. 




Fig. 41. 



This form has been preserved in Germany and abandoned 
in France. 

Figs. 40, 41, and 42 represent the Bunsen cell prop- 
erly so called, with a hollow cylinder of rolled zinc. The 



ACID BATTERIES. 



173 



glass jar is narrowed at the top in order to check the 
evaporation of the nitric acid. 

Sometimes the hollow zinc cylinder is replaced by a 
rod of cast zinc. Siemens prefers a rod of cast zinc 
whose section has the shape of a cross. 

The rod of zinc inconveniently reduces the space occu- 
pied by the dilute sulphuric acid, and consequently the 
quantity of the acid. The other two dispositions seem 




Fig. 42. 

preferable. Here arises the question, Which is the better 
arrangement, the German or the French ? 

The German model contains more nitric acid, which 
may increase and prolong the constancy of the battery. 
But we think the French model ought to be preferred, 
because in the German arrangement the carbon is much 
more expensive, the zinc is not as convenient to amalga- 
mate on account of the strip and ring of copper soldered 
to it, and the expense of the acid is greater. 



174 TWO-LIQUID BATTEEIE8. 



FAUBE'S MODEL. 



English books mention a form of carbon battery which 
deserves notice. The carbon proposed by Fanre has the 
shape of a bottle closed with a carbon stopper. This car- 
bon serves at the same time as porous jar and as negative 
electrode. It contains the nitric acid, and the vapors 
which free themselves force the liquid into the pores of 
the carbon, producing depolarization. 

This form has been but seldom used. It would, how- 
ever, be worthy of study, as it presents economical ad- 
vantages and suppresses nitric-acid vapors, which render 
Bunsen's cell so troublesome and indeed dangerous for 
the men who have the care of a large number. 

ELECTRO-MOTIVE FOBCE AND RESISTANCE 
IN NITRIC -ACID BATTEBIES. 

All physicists agree that the electro-motive force ot 
Bunsen's battery is a little less than that of Grove : the 
difference is very small. 

As to that of Grove's battery, it varies from 1.812 to 
1.512, according to the condition of the acids. 

The resistance of the Bunsen is very feeble, and if 
the Daniell be taken as a term of comparison, it is found 
to vary from 4 to 10 ohms ; while in the Grove battery 
it is less than \ of an ohm, at least in the beginning. At 
the expiration of several hours the resistance will be 
found to have greatly increased ; but if the liquids have 
no longer the same composition, the battery cannot be 
considered as a Grove. We have often said that the re- 
sistance of cells is so variable that no precise information 



ACID BATTERIES. 175 

can be given. Only a general idea of the value of this 
resistance for each kind of cell may be given ; and if one 
desires to replace Bunsen cells by Daniell cells, it is easy 
to obtain the same electro-motive force by doubling the 
number of cells. It is much more difficult, however, to 
obtain as feeble a resistance. For this electrodes having 
large surfaces must be employed, and they must also be 
placed very near each other. This is the means used by 
Carre, as we have shown in Chapter II.; he replaced three 
of Bunsen's cells by five of Daniell's. The same is ob- 
tained with Sir William Thomson's battery. 

MAYXOOTH'S BATTEKY. 

Iron may be substituted for the carbon in Bunseh'g 
battery without sensibly diminishing the electro-motive 
force. The battery may be arranged as follows : 

In a cast-iron pot containing nitro-sulphuric acid — that 
is, a mixture of three parts by weight of nitric acid and 
one of sulphuric acid — is placed the porous jar, which 
contains the amalgamated zinc and water with one tenth 
sulphuric acid. The iron pot serves at the same time as 
negative or conducting electrode and outside jar of the 
battery. The advantages of this arrangement are very 
evident. Those who employed this battery appear to 
have been well satisfied with it, and we cannot imagine 
why it is so little used. 

The part which iron takes in this arrangement has 
given rise to many interesting researches. It is said that 
the iron is rendered passive by its contact with the almost 
saturated solution of nitric acid. 



176 TWO-LIQUID BATTEKIE3. 



DAKIELL'S EXPEKIMEOTS UPON THE SIZE 
AND PLACE OF THE ELECTKODES. 

"We have explained, in speaking of single-liquid bat- 
teries, the advantage of giving a much larger surface to 
the negative electrode than to the positive. Those rea- 
sons do not apply to completely depolarized batteries, such 
as those of Daniell and Grove. It may be said that the 
surface of either electrode can be indifferently increased 
or reduced ; we mean that the reasons which should lead 
to the arrangement of the battery are simply those per- 
taining to economy and practical convenience, and that 
the electro-motive force is the same in both instances. 

Daniell has made some very conclusive experiments 
with regard to this subject. He constructed two Grove 
cells of identical dimensions. In one the soluble elec- 
trode was in the shape of a large zinc wire, and the plati- 
num had the form of a cylinder and surrounded the 
cylindrical porous jar. In the other, the forms remain- 
ing the same, the platinum was placed in the centre and 
the zinc outside. The intensity when measured was 
found to be essentially the same. 

Daniell repeated this experiment in diminishing the di- 
ameter of the outside cylinder without changing its height, 
and found the same intensity as in the first instance. 
"Whence the very curious conclusion that the internal 
resistance of the cell does not alter when the diameter of 
the zinc cylinder alone is changed, all the parts of the cell 
being concentrically disposed, and the central electrode 
reduced to the size of a wire. The simple reason of this, 
which may at first appear strange, is that if the distance 



ACID BATTEEIES. 177 

of the electrodes increases, the average section of the 
liquid increases in exactly the same proportion. 

A close examination will show that this rule ceases to 
be true when the central electrode is of a certain size ; 
in this case there is always an advantage in diminishing 
the distance between the electrodes and in increasing the 
dimensions of the electrode in the porous jar. 

CHLORIC -ACID BATTERY.- 

In a series of very varied experiments a chloric-acid 
battery was tried. This acid, when dissolved, furnishes 
relatively active results, which increase in energy as the 
solution approaches saturation. 

Although this battery can never be employed in the 
practice, we mention it in order to show that cells can 
be made after the model of those of Grove or of Bun- 
sen. 

CHROMIC -ACID BATTERY. 

The battery in which the depolarizing agent is a mix- 
ture of bichromate of potass and sulphuric acid is some- 
times designated by the above name. If free chromic- 
ium acid has ever been employed, it has only been in 
scientific experiments ; it is impossible to make use of 
it in practical applications. 

VARIOUS ACID BATTERIES. 

It has been proved that hydrochloric acid has no de- 
polarizing property, since hydrogen has no effect upon 
this acid. 



— 



178 TWO-LIQTTID BATTEBIES- 

Upon tlie other hand, it has been established that a 
mixture of nitric and hydrochloric acids has a very 
marked action, which, is easily understood, as this mixture 
is a very energetic oxidant and very readily absorbs the 
hydrogen. 



CHAPTEE VI. 
OXIDES U BATTERIES. 

We have seen that oxygenated acids cause the depolar- 
ization of the conducting electrode with which it is placed 
by being decomposed and oxidizing the hydrogen to form 
water. 

Analogous results may be obtained by using oxides, 
such as the peroxide of lead and the bioxide of man- 
ganese. 

Every oxide easily decomposed — the bioxide of hydro- 
gen, the bioxide of silver, the oxide of mercury — would 
give much energy to the batteries in which they are used, 
but the instability of the bioxide of hydrogen, as well as 
the cost of the others, does not permit the use of these 
substances in the practice. 

PEROXIDE -OF -LEAD BATTERY. 

About thirty years ago De La Rive constructed a bat- 
tery in which depolarization was effected by means of 
peroxide of lead. He put the peroxide in a porous jar 
containing a plate of platinum, and thus obtained a bat- 
tery whose electro-motive force was superior to that of the 
Bunsen. We believe that a plate of lead or of carbon 
would have done just as well, and would certainly have 
cost less. 

Unfortunately, we do not know whether the depolari- 
zation was complete or not. We believe that by 



180 TWO-LIQUID BATTERIES. 

employing ordinary minium and by mixing it with 
pieces of crushed carbon, as we have several times 
recommended in the foregoing, a very economical and 
satisfactory battery might be obtained. 

It must be noted, however, that if at the same time 
sulphuric acid is used with the zinc, there will be a 
formation of sulphate of lead, which, on account of its 
insolubility, might check further action. It will be 
remembered that the advantages of the Daniell battery 
consist in the great solubility of the salt formed (sulphate 
of zinc). Whatever may be done, and from whatever 
stand-point batteries may be regarded, one is always led 
to the choice of Daniell's sulphate-of -copper battery as a 
model. 

PEROXIDE -OF -MANGANESE BATTEEY. 

At the same period De La Rive made another battery, 
analogous to the preceding one, by substituting peroxide 
of manganese for peroxide of lead. He found, however, 
that this battery was inferior to the preceding one. 

It is certain, in effect, that the manganese battery 
ought to have a much smaller electro-motive force than 
the peroxide-of-lead battery, and that the depolarization 
ought to be very imperfect. Whatever may have been 
the reasons, this battery was completely forgotten when 
Leclanche commenced his researches, which resulted in 
the production of one of the most extensively used and 
best batteries, for certain instances, ever invented. 

LECLANCHE'S BATTEEY. 

A cell of this battery is shown in Fig. 43. The 
outside glass jar is square, which allows the placing of a 



OXIDES IN BATTEEIES. 



181 



large number in a comparatively small box, thtis render- 
ing the battery less cumbersome. The glass jar is 
narrowed at the top, just leaving room for the cylindrical 
porous jar to be put in or taken out, which almost closes 
the glass jar, thus diminishing any possible evaporation 




Fig. 43. 



of the liquid. The narrow part of the jar is furnished 
with an orifice, through which the zinc is passed, and 
which is also convenient in pouring out the liquid 
contained in the jar. 

The soluble electrode is formed of a simple cylindrical 



182 TWO-LIQUID BATTEKIES. 

piece of zinc, about half an inch in diameter. A little 
hole is made in the centre of the top of the zinc, in which 
a galvanized iron wire is soldered. This connection is at 
the same time flexible and solid ; it may be wound in the 
shape of a helix, which gives it an elasticity frequently 
very convenient. 

The porous jar has, as we have said, about the same 
diameter as the mouth of the glass jar, and contains almost 
equal parts of peroxide of manganese and crushed carbon. 
In the centre of this mass is a bar of carbon, capped with 
lead, to which the positive binding screw is attached. 

The outside jar is about half filled with water and 
ammonia-hydrochlorate. After a short time the liquid 
penetrates the porous jar and enters into the mass it 
contains. 

The mixture of peroxide and carbon is covered with 
wax, to prevent its spilling during transportation. There 
is a hole in this covering to allow the air to escape when 
the water penetrates the porous jar. 

ADVANTAGES OF LECLANCHE'S BATTEEY. 

This battery presents many advantages, which we will 
enumerate : 

1. The zinc is not attacked by the sal ammoniac. 
There is no chemical action in the battery while the 
circuit is open, or, in other words, there is no waste of 
material as long as there is no outside current produced. 
We have already spoken in detail upon this point in the 
description of sal-ammoniac batteries (single liquid) ; and 
we would only say that, from a practical point of view, 
this peculiarity constitutes an incontestable superiority of 
the Leclanche battery over that of Daniell. 



OXIDES IIS - BATTEEIES. 183 

2. On account of the depolarizing action of the 
peroxide of manganese, the electro-motive force at first 
starting of this oell is, as given by Leclanche himself, 1.38 
(Daniell's cell taken as nnit). It has indeed always been 
possible to replace, in the telegraph and analogous appli- 
cations, a certain number of Daniell's cells by a smaller 
number of peroxide-of -manganese cells. Leclanche states 
that twenty-four of his ' cells can replace forty of Dan- 
iell's. 

3. This battery has but a comparatively feeble re- 
sistance, resulting from the conductivity of the peroxide 
of manganese and of the carbon, and also from the 
considerable mass of the conducting electrode. In the 
model, in which the porous jars are 5-J in. high, the 
resistance is between 5-J- and 6 units. 

With equal dimensions the Leclanche has less resistance 
than the Daniell, which constitutes still another superi- 
ority. 

It is evident that if the zinc, instead of being a rod 
half an inch in diameter, were rolled in the form of a cyl- 
inder surrounding the porous jar, as in the usual disposi- 
tion of batteries, the resistance of the cell would be still 
less. As there is no consumption of zinc while the circuit 
is open, there is no inconvenience in increasing its surface. 
Consequently there is a means of reducing the resistance 
of a Leclanche cell, if in any particular instance it might 
be of advantage. 

We will give, further on, the reasons which determined 
Leclanche in the choice of the dimensions given to the 
soluble electrode. 

4. The battery contains no poisonous substances, 
neither does it throw off any acid vapors nor any ap- 
preciable odor. 



184 TWO-LIQUID BATTERIES. 

5. The first cost of the materials is comparatively 
small. 

6.- The battery resists intense cold without freezing, 
and consequently without ceasing to work, which is 
proved by the following experiment : 

A freezing mixture, at — 25° C, was placed around a 
Leclanche cell, in which the thermometer finally de- 
scended to — 16° C, without causing any appreciable 
slackening in the movement of an electric bell upon 
which the cell worked. The cell was shaken or left 
perfectly still, and in neither instance was any weakening 
(with this summary means of comparison) or tendency to 
freeze observed. 

This battery presents, in this respect, still another 
notable advantage over the Daniell, which freezes in 
France during severe winters. The direct experiment 
shows that a saturated solution of sulphate of copper 
freezes at — 5° C, and a concentrated solution of sulphate 
of zinc at — 7° C. 

A recent publication of Leclanche states that the re- 
sistance of his cell varies from 2.33 units at + 10° C. to 
4.22 units at— 18° C, whereas that of the Daniell increases 
from 8.35 at +10° C. to 12.58 at 0° C, and to 14.00 at 
—4° C. If the temperature continues to lower, at— 6° C. 
the liquids become pasty, and towards — 20° C. the re- 
sistance reaches 200 units. 

All this goes to show that the Leclanche battery never 
freezes, and that it should be used in preference to all 
others in all northern countries. 

These advantages are of great practical importance, and 
explain the success of this battery, which is to-day the 
most extensively used -for telegraphs, electric bells, and 
other analogous applications of electricity. 



OXIDES IN BATTERIES. 185 

Any number of these cells may be prepared in ad- 
vance and stored away without putting the liquid in them, 
ready for use at any moment. 

After having been charged, they may be left a long 
time without much evaporation of the liquid and without 
any consumption of the materials. Their form facilitates 
transportation, and is capable of being modified, as will 
be seen, in order to obtain a perfectly closed battery. No 
care is needed for months at a time ; it depends, of course, 
upon the activity of the work to be done. 

The cell furnishes a more intense current than a Dan- 
iell of the same size, and almost as intense as one of Marie 
Davy's cells. 

One must be careful, however, not to use this battery 
for purposes to which it is not fitted : for instance, when 
a continuous current or a great quantity of electricity is 
desired. 

CONSTKTJCTION AND USE. 

1. We have had occasion to speak of the advantage of 
rolled zinc over cast zinc ; we acid that drawn zinc is bet- 
ter than either, as it is more dense and the pores are less 
open. Little scales are sometimes seen to detach them- 
selves from the rolled zinc, which denotes some irregular 
action of the liquids upon the metal. There is nothing 
of the kind apparent with the drawn zinc, undoubtedly 
because it is more homogeneous. 

We have fully explained why, in single-liquid batteries, 
there is an advantage in giving a greater surface to the 
conducting electrode than to the soluble electrode. The 
same reasons hold good for imperfectly depolarized bat- 
teries, such as that of Leclanche ; it is seen how the in- 
ventor reduced the zinc to a small rod. We will again 



186 TWO-LIQUID BATTERIES. 

have occasion to speak of the dimensions of the electrode, 
which is quite a delicate and important question. 

2. Leclanche, in recommending amalgamation of the 
zinc, says : 

" In this battery, where there is no acid, the zinc should 
be used according to the theory, without amalgamation. 
But while the battery is at work the attack upon the zinc 
roughens its surface, thus facilitating the adherence of 
saline crystallizations when the temperature varies .; 
whereas amalgamated zinc always presents a surface free 
from crystals, which fall to the bottom of the jar and do 
not diminish the conducting surface of zinc." 

3. It is very important to employ sal ammoniac as pure 
as possible. That purified by sublimation is the best, al- 
though a little costly. Very good, however, can be found 
which has not undergone this process of purification. 
Care should be taken that the sal ammoniac be not dis- 
solved in vessels of lead, for it would then contain several 
parts of chloride or of sulphate of # lead. This condition 
would cause the loss of the principal advantage of the 
battery ; for a local cell (zinc-lead) would soon form which 
would produce a constant and rapid waste of the zinc and 
sal ammoniac. 

4. It is best to use an almost saturated solution ; there 
is, indeed, no inconvenience in putting a little more salt 
than is necessary in the jar ; it will dissolve in proportion 
as it is consumed by the action of the battery. 

By the action of the battery salts are formed, and 
notably oxy chloride of zinc, which is more easily dis- 
solved in a saturated solution than in a weaker one ; there 
is therefore an advantage in using a saturated solution, 
and it should not be allowed to weaken. In effect, it can 
be understood that if oxychloride-of-zinc crystals attach 



OXIDES IN BATTEKIES. 187 

themselves to the zinc, its active surface is reduced and 
the resistance of the battery increased ; the intensity of 
the battery might thus be greatly diminished. If, how- 
ever, too large a quantity of sal ammoniac be added there 
will be the same result. This salt crystallizes upon the 
surface of the zinc, and the resistance of the battery be- 
comes considerable. There can be no doubt as to the 
truth of this way of explaining things ; for if the zincs be 
cleaned, the resistance will be diminished and the inten- 
sity brought back to its normal value. This observation 
is of great practical importance, because employes of little 
instruction are very apt to attribute to the battery all the 
faults that arise in telegraph offices, without being able to 
distinguish the cause ; they believe the battery to be 
weakened, and think to restore its energy by adding more 
sal ammoniac ; they create, in reality, the fault which they 
intend to correct. 

5. The quality of the bioxide of manganese is also 
very important : that which gives the best results is the 
needle manganese ; it is crystallized, silky, and presents a 
graphite appearance ; if, in addition to these properties, it 
is hard, it possesses very great conductivity. To use it, 
all foreign materials must first be taken off; then it is 
crushed, and finally sifted to get rid of the powder. An 
equal volume of crushed carbon is then added. The 
mixture thus obtained is a very good conductor of elec- 
tricity. 

6. It is very important not to use powdered bioxide of 
manganese. The results of experiments by Leclanche 
show that polarization would be five times greater in a 
cell containing fine powder than in a cell constructed af- 
ter the manner indicated above, with grains of a certain 
size. 



188 TWO-LIQUID BATTEKIES. . 

The resistance of the fine powder reaches 150 or 200 
units ; it is considerably greater than that of the liquid 
with which it is dampened ; consequently the hydrogen, 
instead of distributing itself throughout the whole mass, 
goes straight to the carbon plate and is not absorbed. On 
the other hand, the resistance of the coarser powder, as 
recommended above, is from 12 to 15 units inferior to 
that of the liquid of the battery, and consequently the 
hydrogen is distributed and absorbed in the whole 
mass. 

7. The porous jar should only be half filled with the 
liquid. The inventor says that the dryer the matter con- 
tained in the porous jar the better the conditions of con- 
ductivity and working. 

It will be seen as we advance that, by following this 
order of ideas, he has greatly improved his battery. 

8. There is an advantage in using very porous dia- 
phragms, in order that the action may begin as soon as 
the liquid has been poured in. 

The quality of the porous jars is also very important. 
It appears that those of Wedgwood, though excellent for 
other batteries, are not worth anything in the Leclanche, 
The English have had a good deal of trouble with porous 
jars which chip oft or burst by the solidification of the 
double salts of zinc and ammonium. Neither in France 
nor in Germany has any inconvenience of this kind arisen. 

REVERSED FORM OF LECLANCH^S 
BATTERY. 

In this form the zinc is placed in the central porous 
jar and surrounded by the mixture of peroxide of man- 
ganese and carbon. This disposition necessitates a large 



OXIDES IN BATTERIES. 189 

quantity of manganese as compared with the sal ammo- 
niac, and it is that which led to its being tried. There is 
no doubt as to the slow polarization of the battery thus 
arranged. 

The volume of liquid, however, is much smaller than 
in the original form, which presents a grave inconve- 
nience ; because the liquid has thus to be renewed very 
frequently, and the battery loses many of its advantages. 
In the ordinary battery there is a quantity of manganese 
corresponding to the use of two zinc plates and to two 
charges of sal ammoniac. In the reversed form there is 
enough for the use of six or eight zinc plates and for 
twenty charges of sal ammoniac : it is a marked dispro- 
portion. 

For these reasons the reversed form has obtained but 
little success, and should be only employed in especial in- 
stances. 

AGGLOMERATED - MIXTURE BATTERY. 

As the liquid has less conductivity than the bioxide of 
manganese mixed with carbon, it is easily understood that 
the resistance of the element will be diminished if the 
carbon electrode is well surrounded by the mixture in 
question, rather than by the liquid. 

Leclanche observed that the conductivity increased as 
the matter contained in the porous jar became more com- 
pact ; that is, as the empty spaces filled by the liquid be- 
came less. 

In following up this idea he was led to increase the 
compactness to its maximum, by compressing the mixture 
with a hydraulic press. Porous jars became inconve- 
nient ; he suppressed them and added to the mixture a 



190 



TWO-LIQUID BATTERIES. 



cement which held the mass together, thus constituting 
an agglomerate in which the carbon was tightly held 
which served as the conducting electrode. 

The mixture is composed of 40 parts of bioxide of 
manganese, 55 of carbon, and 5 of gum lac, which serves 
to agglomerate the whole together (Fig. 44). 

Finally, the inventor added in the interior of the ag- 
glomerate 3 or 4 per cent, of bisulphate of potash, which 

facilitates the dissolution of the 
oxy chloride which, in the long- 
run, enters into the pores of the 
mixture. 

The porous jar being sup- 
pressed, some particular- disposi- 
tion must be adopted to prevent 
the zinc from touching the ag- 
glomerate, for if there were con- 
tact between them there would 
be the formation of a local cell 
and lost work. Between the zinc and agglomerate a small 
strip of wood might be placed and the whole be held to- 
gether by two rubber bands. The zinc may also be put in 
a small glazed or unglazed earthenware jar whose walls 
are pierced with holes, which prevents the contact be- 
tween the electrodes and at the same time permits a free 
circulation of the liquid in the outer jar. Two projecting 
rubber bands may be placed around the zinc, which pre- 
vent the contact between the zinc and the agglomerate. 

The agglomerate, once exhausted by long work of the 
battery, is not worth anything ; the zinc which caps the 
carbon may be easily taken off, as also the binding screw 
to which the negative connection of the adjoining cell is 
attached. The mass of carbon and of sesquiqxide of man- 




fffff^—^ 



I 



Eig. 44. 



OXIDES IN BATTERIES. 191 

ganese may be thrown away and the zinc and brass sold 
for old metals. 

LECLANCHE'S AGGLOMEEATE BATTEEY. 

The preceding battery lias not realized the expecta- 
tions of the inventor. It happened that the internal re- 
sistance of the element increased considerably, and that 
consequently the battery gave very unsatisfactory results, 
especially in circuits of little resistance. 

With a view to remedying this inconvenience, Le- 
clanche caused the agglomerate, of which we have spo- 
ken, to be made in the shape of small bricks and com- 
pressed in a hydraulic press. These little bricks are 
placed one on each side of the carbon electrode which 
rises above them ; they are held in this position by rub- 
ber bands, which at the same time hold the rod of zinc 
and the intervening piece of wood. 

" In the old battery," says Leclanche, " the internal re- 
sistance depends upon the conductivity of the agglomer- 
ated mass and upon the adherence of the carbon in this 
mass." The new disposition does away with the inequali- 
ties that this contact produced in the resistance, and which 
were the result of the production of ammonia in the interior 
of the agglomerate at the contact with the carbon pole. 
Consequently in the new battery the resistance only de- 
pends "upon the conductivity of the liquid excitant. 
This conductivity rather tends to increase than to diminish; 
in effect, by the working of the battery, chloride of zinc, 
which is a very good conductor, is formed ; it is only the 
depolarizing power of the agglomerate pressed against the 
carbon which varies." 

Besides, by increasing the number of these little bricks 



192 



TWO-LIQUID BATTERIES. 



placed against the carbon, the internal resistance of the 
element may be diminished at pleasure. Leclanche some- 
times puts one, sometimes two as shown in Fig. 45, and 
sometimes three. 

An incontestable advantage of the new battery is that 




Fig. 45. 



the same elements may be employed indefinitely, and it 
is only necessary to renew the zinc and the agglomerated 
bricks when they are worn. 



OXIDES IN BATTERIES. 193 



CLARKE AND MUIRHEAD'S MODIFICATION 
OF LECLANCHE'S BATTERY. 

The only difference between this battery and that of 
Leclanche is that in the former the carbon electrode 
and indeed the pieces of carbon mixed with the bioxide 
of manganese are platinized This is certainly a very 
good idea, as we mentioned when speaking of Smee's and 
of Walker's batteries. The polarization is thus undoubt- 
edly diminished. 

According to information given by the inventors, this 
new cell, after working one minute in a circuit of 100 
units of resistance, only loses 1 per cent of its electro- 
motive force by polarization, whereas Leclanche's cell 
loses 2-J pei' cent. 

After five minutes the platinized cell only loses 2 per 
cent, while the Leclanche loses 5 per cent. 

After ten minutes the first one again loses 2 per cent, 
and the second 10 per cent ; if the experiment be con- 
tinued, the electro-motive force of the Leclanche cell is 
seen to diminish steadily, while that of the platinized cell 
remains constant. 

This platinized cell has what we have termed the re- 
versed form ; that is, the zinc is in the centre, 'and in a jar 
which is not porous, but whose walls are pierced with 
holes by which the communication between the two ele- 
ments is established. 

The zinc has the form of quite a large cylinder, the 
object of which is to diminish the resistance. The de- 
polarizing mixture is placed around the sides in the out- 
side jar, which disposition also diminishes the resist- 
ance. 



194 TWO-LIQUID BATTEKIES. 

The outside jar, as well as that in the centre, is closed 
with cement, so that all evaporation is prevented. 

All these dispositions had been already tried, and the 
only new idea is the platinizing of the carbon. 

The inventors say that they sometimes platinize the 
fragments of peroxide of manganese. It would be inter- 
esting to examine closely the advantages or inconveniences 
of this process ; it might be inquired whether or not the 
bioxide of manganese would lose its efficiency wlien cov- 
ered with platinum. 

ELECTRO-MOTIVE FOKCE. POLARIZATION. 

Leclanche represented his original cell, with the porous 
jar, as having an electro-motive force equal to 1.38 (Dan- 
ielle 1). These figures are certainly inferior to the real 
value, at least before any polarization. 

We will admit the figures 1.48 as given by Clark and 
Sabine, which is a little less than that of Marie Davy's 
cell. If the circuit in which Leclanche' s battery works has 
a considerable resistance, polarization is very slow. r 

CHEMICAL ACTIOK 

Leclanche represents the chemical action which takes 
place in his cell by the following equation : 

]SrH 3 H01 + 2Mn0 2 + Zn = ZnCl + NH.+ HO + Mn 2 3 

The zinc combines with the chlorine of the ammonia 
hydrochlorate and forms chloride of zinc ; ammonia is set 
free ; the hydrogen given off under these actions, and which 
would polarize the carbon without the presence of the 
bioxide of manganese, becomes oxidized, forming water, 
and the peroxide is reduced to sesquioxide of manganese. 



OXIDES IN BATTERIES. 195 

If it be agreed to give the name of chloride of ammo- 
nium to that salt which we have called ammonia hydro- 
chlorate, there would in reality be nothing changed, but 
its formula would be NH 4 C1. It could be said that the 
zinc is substituted for the ammonium, that the ammonium 
is decomposed into ammonia and into hydrogen, etc. etc. ; 
but this manner of expression should be preferred here, 
for Leclanche has established that the ammonium acts 
more favorably in the presence of the bioxide of man- 
ganese than the hydrogen alone would ; it is indeed for 
this reason that sal ammoniac ought to be preferred to 
other alkaline chlorides, such as chloride of potassium, 
chloride of sodium. 

We ought to say, however, that this theoretical reac- 
tion in Leclan die's battery is not the only one that takes 
place. First, it is plain that when the battery polarizes, 
]t is undoubtedly because the hydrogen is deposited upon 
the carbon and does not oxidize at the expense of the bi- 
oxide of manganese. Then is made manifest the forma- 
tion of double salts, oxychloride of zinc, and double chlo- 
ride of zinc and ammonium. These salts are but slightly 
soluble and obstruct, the action. A saturated solution of 
sal ammoniac is needed to dissolve them, which explains 
one of the practical recommendations made above. 

We are thus again led to remark upon the complicated 
nature of the chemical actions in batteries, and #o say with 
Mr. Gladstone "that, since the elucidation of the tele- 
graph, batteries have been studied more from a mechanical 
and electric point of view than from a chemical stand- 
point, . . , and that there is much left to be done 
in regard to this matter." 

It is seen from the theoretical equation of the battery 
that ammonia is set free, and that is what the experiment 



196 /TWO-LIQUID BATTEEIES. 

shows ; but in the ordinary practice of the telegraph the 
work is so intermittent, and the corresponding chemical 
actions so slow, that no odor of ammonia is noticed at all. 

It should here be repeated that Leclanche did not choose 
sal ammoniac by chance. He tried sea-salt (chloride of 
sodium) and chloride of potassium, and he has shown that 
they are all very inferior to the sal ammoniac. 

Any one can make the experiment with sea-salt and 
show, as we have done, that the electro-motive force of 
the battery thus modified is very much less than that of 
the Leclanche battery properly so-called, and that it polar- 
izes rapidly. Consequently, if in any emergency the 
battery has to be charged with sea-salt instead of sal am- 
moniac, and a sufficient current is obtained, it must not 
be believed that a new invention has been made, nor even 
a good one. 

WEAKENING OF THE LECLANCHE 
BATTEEY. 

The bioxide of manganese does not produce complete 
depolarization ; and if the resistance of the outside cir- 
cuit is very small, the electro-motive force diminishes rap- 
idly. It is only necessary to close one of Leclanche's 
cells upon itself for a few seconds to polarize it in an ap- 
preciable manner. But if the current be interrupted 
after a short time, the battery will soon recover its initial 
force.! This is the phenomenon of polarization in all its 
simplicity. If the battery only works intermittingly, as 
in the telegraph in general, there is very little polariza- 
tion, in which case the battery is perfectly irreproachable, 
and deserves to be preferred to those of Daniell and of 
Marie Davy. 



OXIDES m BATTERIES. 197 

If, on the other hand, the Leclanche battery be made to 
work uninterruptedly, its electro-motive force is seen to 
decrease in a manner very interesting to watch. 

Gaugain has studied this weakening under conditions 
well determined by measurements of the intensity of the 
current. 

The following are the results : 

Electro-motive Force. 

At the start, May 28th 288 

June 1st 213 

Aug. 6th 199 

Sept. 2d 180 

" 3d 152 

This weakening would have been more rapid had the 
resistance of the circuit been less, and less rapid with a 
greater resistance. • 



PKACTICAL DUKABILITY OF THE LE- 
CLANCHE BATTEKY. 

We have said several times that this battery possesses 
the great advantage of dispensing with all care during 
long periods, on condition, however, that it only be em- 
ployed for those purposes for which it is suited. 

We ought again to speak of this very important sub- 
ject. 

The principal French railway companies have furnished 
us with the following official and incontestable, though 
very astonishing, information : 

A battery at V furnishes a continuous current, causing 
an electric bell to ring about t wen ty-three hours every day ; 
it has needed no care during eleven months. 

When the batteries at E, at Y, and at M were exam- 



198 TWO-LIQUID BATTERIES. 

ined in 1876, zincs were still found which had been placed 
there in 1867. 

Finally, a battery at O worked from July 26th, 1867, 
to August 12th, 1876 ; being recharged at that date, the 
zincs were renewed before there was any absolute neces- 
sity. During those nine years of service the sal ammo- 
niac was only renewed once, and this is the only expense 
occasioned by that which may be considered as the aver- 
age work of a railway station. This is the most striking 
example that has been given to us, and it leads one to 
believe that it would be difficult to imagine a better bat- 
tery for branch offices than that of Leclanche. 

It is understood, of course, that these extraordinary pe- 
riods of duration are obtained by intelligent attention, or 
rather by the absence of any carelessness or misunder- 
standing. The battery at O was never touched except by 
the superintendent of the telegraph, who followed the 
experiment with great interest. 

The best telegraph service is to be found in those of- 
fices where the least quantity of sal ammoniac is consumed. 
An intelligent inspector would always be able to distin- 
guish the causes of the numerous hesitations in the tele- 
graph, and act accordingly; whereas another would at- 
tribute every failing to the weakening of the battery, and 
would inconsiderately hasten to remedy it by adding too 
great a quantity of salt. 

We ought here to point out the mistaken idea of the 
necessity of moving the battery to increase its force ; some 
think it well to shake it in order to awaken it, as they 
would do a person asleep. This is a great mistake in the 
management of the Leclanche battery, which, it is recom- 
mended, should be kept perfectly quiet. 

We have already had occasion to say that the best ]3lace 



OXIDES IN BATTERIES. 199 

for a telegraph battery, or for one doing analogous work, 
is a cellar in which the temperature varies but slightly ; 
we can only repeat this piece of advice at present. The 
heat in offices is rather injurious, as it occasions an active 
evaporation. 



OHAPTEE YII. 

CHLORIDE BATTERIES. 

The depolarization of the conducting electrode is 
generally effected by oxygen, but it can also be done by 
chlorine, as will be seen in the batteries which we will 
now describe. 

CHLOKIDE- OF -PLATINUM BATTERY, 

We only mention this battery, not admitted in prac- 
tice, because Daniell points it out as a model of a perfect 
battery. After having described his sulphate-of-copper 
battery, he adds : 

" The surface of the conducting electrode is thus per- 
petually renewed by the deposit of pure copper, and the 
contrary action of the zinc and of every other metal pre- 
cipitated is successfully prevented. The affinity of the 
copper for the acid, though less,, exists, however, and this 
opposition could not be prevented except by the use of 
platinum electrodes, whose surface would be continually 
renewed by the decomposition of chloride of platinum ; 
this apparatus would be perfect, but very costly. ..." 

It is probable that Daniell intended the cell to be com- 
posed as follows : zinc, dilute sulphuric acid ; chloride of 
platinum, platinum. 

Under these conditions, the depolarization would be 
effected as in the Daniell ceil, only that the hydrogen 
would be burnt by the chlorine instead of by the oxygen. 



CHLORIDE BATTERIES. 201 

The principal action of the battery would still be that of 
the sulphuric acid upon the zinc, and the decomposition 
of the chloride of platinum would be less of an obstacle 
to the principal action than that of the sulphate of copper 
in the Daniell. The electro-motive force of the chloride- 
of -platinum battery ought to be much greater than that 
of the sulphate-of -copper battery. 

CHLORIDE- OF -SILVER BATTERY. 

Marie Davy appears to have been among the iirst to 
employ chloride of silver. In 1860 he wrote the fol- 
lowing : 

" I have constructed a battery formed of zinc, pure 
water, and chloride of silver melted in a silver crucible, 
and it has worked with perfect regularity. Its internal 
resistance, at first very great, has gradually diminished in 
proportion as the chloride of zinc formed has been dis- 
solved in the water. By previously dissolving this salt, 
the battery immediately furnishes a strong current. The 
chloride of silver is completely reduced throughout all its 
parts, always preserving its shape. The insolubility of 
the reducible salt becomes an advantage, as it dispenses 
with the use of porous jars. ..." 

During the same year we studied this battery, using 
a porous jar and undissolved chloride of silver ; our elec- 
trodes were of copper and amalgamated zinc. We found 
the electro-motive force to be apparently equal to that of 
the Daniell. 

These experiments possess in themselves but little 
interest. It is only since Warren De La Rue has given 
his attention to this battery that it has attained any impor- 
tance, and that its use has become genei : al. 



202 TWO-LIQUID BATTERIES. 

In the beginning of his researches, this physicist used 
chloride of silver in the shape of a powder or paste, and 
his liquid was a thin solution of sea-salt. A little incon- 
venience in this battery has been pointed out to us. It 
appears that it evolves gas, and that, consequently, if the 
glass jar be hermetically closed the pressure of the gas 
causes it to burst. 

It is clear that this gas is only an inconvenience when 
the jars are tightly closed, and that its gravity should not 
be exaggerated. 

At all events, we believe that the form which De 
La Rue has given to the battery does not present this 
little disadvantage, and that it contains several very inter- 
esting dispositions. Figure 46 represents a battery of ten 
cells, each of which is composed in the following manner : 

The outside cylindrical jar is about 5 in. high and 
1J in. in diameter. The soluble electrode is formed of a 
rod of unamalgamated zinc, but of very good quality. In 
the upper part of this zinc rod is bored a hole, in which 
a strip of silver (positive connection of the adjoining cell) 
is held by means of a small brass wedge, which assures 
a perfect contact between the zinc and the silver. 

The other electrode is formed of a strip of silver 
around which is melted a cylinder of chloride of silver, 
AgCl, represented separately in the figure. 

To avoid an accidental contact of the two electrodes, 
the rod of chloride of silver is placed in a small cylinder 
of parchment paper, A ; there are two holes near the top 
of this paper cylinder, through which the strip of silver 
passes, as shown in B. 

The liquid is a diluted solution of sal ammoniac ; the 
best proportion is that of 23 grammes of chloride of 
ammonium to 1 litre of distilled water. 



CHLORIDE BATTERIES. 






( F^ESE 



IS 




Fig. 46. 



204 TWO-LIQUID BATTEEIES. 

The outside jar is closed with a paraffin stopper through 
which the zinc passes ; the strip of silver passes between 
the stopper and the glass jar. The figure also shows that 
there is a hole made in the paraffin stopper, through 
which the liquid is poured in by means of a small fun- 
nel, and then the hole is closed with a small paraffin cork. 

The choice of this material presents important advan- 
tages. First, paraffin is one of the best insulating sub- 
stances, which is of great importance when several thou- 
sand cells are joined in intensity, as De La Rue does. 
Then it is absolutely antihygrometric, so that if a little 
water be dropped upon its surface it collects in many 
little globules and does not spread over the surface, which 
might destroy the insulation. The air does not deposit it- 
self upon it as upon glass, for instance, whose surface 
thus covered with steam becomes a conductor. Finally, 
paraffin melts when slightly heated. The jar may be her- 
metically closed by means of a small iron wire, flattened 
at the end and slightly heated, which is passed around 
the zinc where it comes through the cork, and also around 
the paraffin stopper which closes the orifice for the intro- 
duction of the liquid. 

The action in this battery is very simple : the zinc is 
dissolved and takes the place of the silver in the chloride ; 
the silver is deposited in a porous mass first upon the 
surface and then in the mass of the chloride. 

The capital advantage of this battery, as in all where 
zinc with sal ammoniac is used, consists in the absence of 
any local or internal action as long as the electric circuit 
is open ; in other words, this battery does not work upon 
itself. This circumstance is very important, for these 
cells are only used in experiments of short duration and 
long intervals ; it is necessary to find the battery, eight 



CHLORIDE BATTERIES. 205 

days later, in exactly the same state in which it was left 
eight days previous. 

In the first moments of the action the current is very 
feeble ; this is caused by the great resistance, for the con- 
ductivity of the chloride of silver is very little and the 
exposed surface of the silver electrode is very small. 
But at the end of a certain time the surface of the chlo- 
ride is covered with silver, its conductivity is increased, 
and the intensity attains its normal value, which varies 
but little afterwards, as is shown by the following table 
of experiments made by De La Rue with a voltameter : 

Gas per Minute. 

At the start, June 29th, 1875. 1 cent. cube. 

July 4th, " 1.4 " 

Oct 27th, " 1.4 " 

March 15th, 1876 1.45 " 

April 8th, '• 1.41 " 

The electro-motive force^of these cells differs very little 
from that of the Daniell. De La Rue found it to be 0.97 
with sea salt, and 1.03 with sal ammoniac. 

The resistance is about 4.3 ohms, as nearly as could be 
ascertained. 

For the above-mentioned experiments De La Rue col- 
lects 200 cells upon a single board ; they pass through a 
slab of ebonite, which is a better insulator than wood. 

Six of these batteries of 200 cells each are placed one 
above the other in a carefully constructed closet which 
protects them from dust or from accidents. 

This is not the place to enlarge upon De La Rue's ex- 
periment. We would only say that he has again proved 
that electricity generated by batteries differs in no way 
from that generated by electric machines, and that if a 
sufficient number of cells be joined to form a battery, a 



206 TWO-LIQUID BATTERIES. 

continuous spark is observed when the extremities of the 
two connections are brought in close proximity to eacli 
other. De La Rue has collected as many as 8000 cells in 
one battery, many more than any one had previously col- 
lected, and he proposes soon to make a battery of 12,000 
cells. 

There can be no polarization in the experiments made 
by this physicist, as they last but a short time and are 
made at such long intervals, as is the case in nearly all 
purely scientific experiments. But Du Moncel has made 
some direct experiments which prove that after the cir- 
cuit has been closed twenty hours the battery shows no 
polarization ; and if, in fact, the action takes place as we 
have said — that is, the simple substitution of zinc for sil- 
ver in the chloride — there is no hydrogen set free, and 
consequently no polarization. As the deposit of silver 
upon the conducting electrode does not change the na- 
ture of the latter, the conditions are the same as in the 
Daniell battery, which is the model of completely depo- 
larized batteries. 

GAIFFE'S BATTERY. 

The chloride-of-silver battery is very extensively used 
by Gaiife for induction-coils or to furnish continuous cur- 
rents used for medicinal purposes. 

His cells are very small" and hermetically closed in 
ebonite boxes having screw tops. 

In those batteries which are destined to be transported 
frequently from one place to another there is no free 
liquid; the two electrodes are separated by six or eight 
sheets of blotting-paper saturated with a solution contain- 
ing 5 per cent of chloride of zinc. 



CHLORIDE BATTERIES. 



207 



Gaiffe lias employed powdered chloride of silver, but 
he now seems to prefer the melted chloride. 

The residue of the battery is silver, and if it be kept 
and given back to the manufacturer its use is very 
economical. 

Figure 47 represents another cell which stands on end, 
and in which liquid is placed as in ordinary batteries. 

The electrodes are, as is seen, attached to metallic pieces 





Fig. 47. 



which pass through the top, and to which are fastened 
the connections of the adjoining cells. 

There is no waste in these batteries when the circuit is 
open, which is of great advantage. It is important to 
note that, in order not to lose this advantage, the top must 
be kept perfectly dry, for the least humidity that might 
join the electrodes would establish a circuit and produce 
a constant working in the cell. 



208 TWO-LIQUID BATTEEIES. 



CHLOEIDE - OF - LEAD BATTEEY. 

Marie Davy tried the use of chloride of lead, but the 
electro-motive force thus obtained was less than the unit 
(Darnell's cell). There is therefore no advantage in its 
use, for chloride of lead is comparatively dear. 



PEBCHLOBIDE-OF-IBCXN" BATTEEY. 

In 1866 Duchemin proposed the use of perchloride of 
iron as depolarizing agent. This substance is pointed out 
as containing a quantity of chlorine, as are the peroxides 
of lead and of manganese, which contain large quantities 
of oxygen. 

The battery in question has an electrode of zinc im- 
mersed in a solution of sea-salt, and an electrode of car- 
bon in a solution of perchloride of iron. 

The hydrogen given off by the action of the zinc upon 
the water goes straight to the carbon and decomposes the 
iron salt, which is transformed into protochloride. 

The hydrochloric acid, formed by the combining of 
the polarizing hydrogen and the chlorine set free from 
the perchloride, contributes to the dissolving of the zinc 
and to the intensity of the battery. 

This cell is not constant ; first because depolarization is 
not complete, and again because there are deposits^ pos- 
sessing little conductivity, made upon the zinc. 

Du Moncel has shown that the electro-motive force of 
this battery is, at first starting, very superior to that of 
Marie Davy's battery, and inferior to that of Bunsen's 
battery. 



CHLORIDE BATTERIES. 209 

The figures are : 

Bunsen or Grove cell 11,123 

Perchloride of iron ,* 9,640 

Marie Davy's sulphate -of -mercury cell 8,192 

The contrivance proposed by Duchemin would there- 
fore appear worthy of study. It is probable that, by 
means of some chemical or physical artifices, the con- 
stancy of this battery might be increased. 

The mixture of pieces of carbon with the perchloride 
of iron has already been tried, and with good results. 



CHAPTER VIII. 
DEPOLARIZING - MIXTURE BATTERIES. 

We have seen in the previous chapters that the constant 
preoccupation of physicists should be to depolarize the 
conducting electrode by surrounding it with those bodies 
from which oxygen or chlorine is easily freed. These 
gases combine with the gases evolved by the action of 
the battery, and prevent or diminish the polarization of 
the electrode. Instead of employing bodies which furnish 
oxygen or chlorine by their decomposition, a mixture of 
two substances, whose reciprocal reaction produces oxygen 
or chlorine, may be placed around the electrode. 

A battery may therefore be made by using any of the 
means indicated in works upon chemistry for the prepara- 
tion of oxygen or chlorine. 

We will examine the most important of these batteries, 
commencing with those in which oxygen is the depolariz- 
ing agent. 

POTASSIUM -CHLOEATE AND SULPHURIC- 
ACID BATTERY. 

In 1859 Messrs. Salleron and Renow presented to the 
French Academy of Sciences a battery in which depolari- 
zation was effected by means of a mixture of potassium 
chlorate and dilute sulphuric acid. 

This battery appears not to have been used except in a 
few experiments made by the inventors. Its failure, how- 



DEPOLAKIZING-MIXTURE BATTEEIES. 211 

ever, may have been due to some secondary cause, and wo 
believe that the idea might be carried out, and with very 
good results. 

The electro-motive force of this battery is less than that 
of Grove's cell, but greater than that of the Daniell. 

The inventors call attention to the fact that the potas- 
sium chlorate destroys live times the quantity of hydrogen 
that sulphate of copper does, and that its cost is only 
about three times greater, whence their justifiable con- 
clusion that the battery ought to be economical. 

Unfortunately we have not been able to ascertain 
whether the depolarization is complete or not ; we have 
not had time to make the experiment ourselves. 

ANALOGOUS COOTKIVAJSTCES. 

Potassium chlorate could be replaced by chlorate of 
sodium, and the chlorates by the nitrates. 

The mixture of nitrate of sodium and sulphuric acid 
has been tried, and it presents several economical advan- 
tages, because nitrate of sodium is a very cheap salt found 
in large quantities in South America. 

We do not believe that this battery has ever been used 
in the practice, but we do not know what disadvantages 
it might possess. 

BICHKOMATE- OF -POTASSIUM AND SUL- 
PHUPJC - ACID BATTEEIES. 

Among the many known means for the preparation of 
oxygen, there is one which consists in putting bichromate 
of potassium and acidulated water in a retort. The reae. 
tion is indicated by the following equation : 



212 TWO-LIQTJID BATTERIES. 

K0.2Cr0 3 + 4S0 3 = Cr 2 3 , 3S0 3 + KO.S0 3 + O, 

That is, an alum (double salt having the formula 
Cr 2 3 , 3S0 3 -f- KO.S0 3 ) and oxygen are formed. 

The use of this mixture for depolarizing the conducting 
electrode was an idea of Poggendorff , who thus conceived 
a very interesting voltaic combination, which has received 
many applications under the great variety of forms given 
to it by the constructors. 

The most simple form of this cell is the same as that of 
the Bunsen : amalgamated zinc in a glass or earthenware 
jar, porous jar in the centre of the zinc cylinder, carbon 
in' the porous jar. In the outside jar is sulphuric acid 
diluted with twelve times its weight of water. In the 
porous jar is a mixture composed as follows : 

100 parts of water. 
12 " " bichromate of potassium. 
25 " " sulphuric acid. 

This battery thus charged has an electro-motive force 
greater than that of any battery that we have as yet 
studied ; it is equal to 2028 volts, according to Clark 
and Sabine, which means that it is double that of the 
Daniell cell. 

It is true that W. H. Preece, Electrician of the Post- 
office, England, found it to be equal to 1.97 at its maxi- 
mum, with a liquid composed a little differently, of which 
we will speak as we proceed. But even admitting this 
latter value, it is seen that the electro-motive force of the 
battery in question is greater than that of either Grove's 
or Bunsen's battery. 

It must be added that this extraordinary electro-motive 
force is only realized at first starting, for the battery 
polarizes rapidly, at least if placed in a very short circuit. 



DEPOLARIZING-MIXTURE BATTERIES. 213 

The conclusion to be drawn from this last observation 
is that Poggendorff's depolarizing mixture accomplishes 
but incompletely its object ; for this reason his idea, 
however ingenious it may be, cannot be placed side by 
side with the inventions of Daniell or Grove. 

It is important to note that the two substances of 
which the mixture is composed act upon each other inde- 
pendently of any action of the battery ; consequently the 
liquid ceases, after a certain time, to possess any depolar- 
izing virtue. In 1S41 Bunsen suggested a much more 
complex mixture of chromate of j>otash, chloride of potas- 
sium, bioxide of manganese, and common salt. Wiede- 
mann says that this mixture gives less satisfactory results 
than that suggested later by Poggendorff. . 

CHEMICAL ACTION IN THE BICHROMATE 
BATTEEY. 

Poggendorff gives the following as the composition of 
the mixture to be placed around the carbon : 

Bichromate of potash 3 parts. 

Sulphuric acid 4 " 

Water 18 " 

Another composition, as suggested by Wohler and Buff, 
is : 

Bichromate of potash 12 parts. 

Sulphuric acid 25 " 

Water 100 " 

It is with this latter mixture that the measurements for 
the electro-motive force stated above were taken, and it 
is that which is used in the German telegraphs. 

Many other proportions have been suggested, and there 



214 TWO-LIQUID BATTERIES. 

prevails concerning this subject a certain confusion which 
we will endeavor to do away with. 

It should be well understood that we are now speaking 
of batteries of two liquids, separated by a porous parti- 
tion.* 

Returning to the equation representing the nature of 
the chemical action produced by the reaction of the sul- 
phuric acid upon the bichromate of potash, it is seen that 
four equivalents of sulphuric acid must be made to react 
upon one of bichromate. 

Bichromate of potash is an anhydride, whose equivalent 
is: 

KO 47.11 

2Cr0 3 100.56 



147.67 



Sulphuric acid, the rnonohydrate, has the following 
equivalent : 

S0 3 40 

HO 9 



and four equivalents have a weight equal to 49x4=196. 
Thus the theoretical proportion is that of 147 to 196, 
or in round numbers 150 to 200, which is that of 3 to 4 
as indicated by Poggendorff. We repeat once more that 
it is the sulphuric rnonohydrate that we speak of. If 
ordinary commercial sulphuric acid were used, the propor- 
tion of 3 to 4 would no longer be in accordance with the 
theory (which we have just exposed). 



*We will speak later of bichromate batteries without porous jar, 
which are termed (wrongly, according to our idea) single-liquid 
batteries. The composition of the liquid ought to be different. 



DEPOLAEIZIjSTG-MIXTURE batteries. 215 

It must be admitted that the proportion as indicated by 
Poggendorff has only a theoretical value, because the com- 
mercial sulphuric acid which is necessarily employed in 
the practice is not a monohydrate, but contains more 
water. 

It is probable that "Wohler and Buff increased the pro- 
portion of sulphuric acid because they found that an ex- 
cess of the acid facilitated the action ; perhaps they also 
observed that the conductivity of the liquid was greater 
with the composition they suggest. 

If we were studying batteries without porous jar, the 
proportions ought to be very different ; the reaction may 
be represented by the equation : 

3Zn + K0.2CrO,+ TSO.HO = 3ZnO.SO,+ Cr 2 3 3S0 8 
+ KOSO. + 7HO 

Therefore, one equivalent of bichromate of potash 
(147.67) and seven equivalents of sulphuric monohydrate 
(49x7=31:3) are theoretically necessary, say in round 
numbers 3 to 7. 

Mr. Byrne recommends the following mixture, in which 
the proportion of sulphuric acid is still greater than that 
indicated by the preceding calculation : 

340 grammes of bichromate of potash. 
925 " " sulphuric acid. 
2500 " " water (2i litres). 

The proportion of 925 grammes of acid to 2500 litres 
of water is greater than that which corresponds to the 
maximum of conductibility of the mixture (see Table IY. 
at the end of the book). But it must be taken into con- 
sideration that, as soon as the battery begins to work, the 
acid weakens ; therefore it is quite justifiable to put a 
larger quantity than is necessary at first starting. 



216 TWO-LIQUID BATTEEIES. 



-APPLICATION TO THE TELEGRAPH. 

The bichromate-of -potash battery is employed in Prus- 
sia in very important offices. Its considerable electro- 
motive force has caused it to be preferred to the Daniell 
(Meidinger's balloon form) in all places where there is an 
especial person to take care of it, and where the handling 
is not of such great importance. 

On account of its great electro-motive force and its fee- 
ble resistance, this battery is well suited to those offices 
where work is done on several lines at once with a single 
battery. 

" The necessity of frequently renewing the elements,' 1 
says Dr. Dehms, " is an inconvenience, but there is no 
difficulty in the operation. ' The Commission ' has in- 
part avoided this inconvenience by proposing the con 
struction of very large cells. The large quantity of ma- 
terial that they are able to hold necessitates a less fre- 
quent renewal. 

" The electro-motive force and the resistance vary in an 
unfavorable manner from the beginning until the battery 
is completely exhausted. The electro-motive force dimin 
ishes but slightly, and the resistance increases considera- 
bly. In order to obtain a greater constancy, a certain 
number of elements may be changed at regular intervals, 
and not the whole battery at one time." 

The elements used by the German Government are dis- 
posed as has been described when speaking of the German 
model of Bunsen's battery. 

The carbon, having a height of 6-g- inches and an exte- 
rior diameter of 3| inches, is placed in the outer jar, 
around the porous jar; its walls are pierced with nine 



DEPOLAKIZING-MIXTURE BATTERIES. 217 

holes at different heights, in order to facilitate the circu- 
lation of the liquid. A copper ring is closely laid around 
the upper part, which has previously been immersed in a 
bath of paraffine, as we have explained in speaking of 
other batteries, to prevent the attack on the metal by the 
acids ; this ring is separated from the carbon by a thin 
strip of tin. 

The zinc is placed in the porous jar and is cross-shaped, 
which gives a considerable surface with a comparatively 
small mass. 

The liquids used are : with the zinc, sulphuric acid 
diluted with 20 times its bulk of water ; and with the 
carbon, one part by weight of bichromate of potash, two 
parts of sulphuric acid and eight of water, the latter liquid 
being the theoretical mixture indicated by Buff. 

We believe it is well in this battery to give a large sur- 
face to the carbon, and to place it in the outer jar; the 
battery not being completely depolarized by the mixture, 
there is an advantage, as we have several times repeated, 
in increasing the size of the conducting electrode. As 
the liquids are not subject to evaporation, there is no in- 
convenience in increasing the quantity of that liquid 
which produces the depolarization. The disadvantages of 
the cast-zinc disappear with the amalgamation, at least if 
the amalgam is renewed frequently enough. 

Dr. Dehms calls this a Bunsen battery, with chromic 
acid. We believe, however, basing our opinion upon the 
authority of Wiedemann, that this is a misnomer. 

GAUGAIlSrS EXPEKIMENTS. 

G-augain has given the results of several very interest- 
ing experiments with bichromate-of-potash batteries. 



218 TWO-LIQUID BATTERIES. 

He lias shown that chrome alum forms in the battery 
even when not at work, but that the electro-motive force 
is only slightly diminished by this alteration in the liquid ; 
it only varies from 296 to 278 in four months (open 
circuit). 

He found that by causing the battery to work upon an 
electric bell night and day, the electro-motive force was, 
after 17 weeks' work, still superior to that of the Daniell 
cell. 

These figures show that the battery in question, although 
less constant than the Leclanche, is still a good battery, 
especially when a large number of cells are to be collected 
together in a limited space. It will furnish an equal cur- 
rent with fewer cells. There will be no freeing of gases 
or odors, and it will only require more frequent attention. 



USE IN ENGLAND. 
FULLER'S BATTERY. 

The bichromate-of-potash battery has also been em- 
ployed in England since 1877, under a form given to it 
by Fuller, The zinc plate is placed upright in the porous 
jar, and held in this position by means of a kind of ring 
at the bottom. It should be carefully amalgamated, as 
also the copper wire which rises from the bottom and 
serves as the connection. Finally, an ounce of liquid 
mercury is put in the bottom of the porous jar, as we have 
seen done by Tyer and other electricians. 

The carbon does not surround the porous jar as in the 
German model ; it is a simple plate 6 in. by 2 in., and 



DEPOLARIZING-MIXTUKE BATTERIES. 219 

provided with a metallic cap to which a clamp screw is 
attached. 

We owe to Mr. Spagnoletti some very interesting infor- 
mation upon the results obtained from the use of this 
battery upon the Great Western Railway, England. 

He estimates its electro-motive force at 2 volts and its 
resistance at 1 ohm, for the model whose capacity is one 
litre. At Paddington Station the service, directed upon 
11 lines, varying from 42 to 284 miles, is done at present 
with 61 of Fuller's cells only.* 

This battery worked actively night and day the whole 
of the year 1878, during which time sulphuric acid was 
added ten times and bichromate only five times. At 
the end of December the cells were dismounted and 
thoroughly cleaned ; several zinc plates had to be replaced. 

It is seen that the care of the battery is reduced very 
much ; and indeed during the first three or four months 
no attention whatever is necessary. 

Mr. Spagnoletti considers this battery as very conve- 
nient for branch offices ; and indeed, when compared with 
the Daniell, the reduction to one half of the number of 
cells is no small advantage. 

The cost of keeping the battery in order is not very 
great, as the carbon ought to last a long time, and the 
zinc from twelve to eighteen months ; the sulphuric acid 
and the bichromate are substances which cost very little. 

It appears that there are already 20,000 cells in use in 
England, which is proof of a great success. We know from 



* It is interesting to note that at Paddington Station 64 of 
Fuller's cells replace 575 of Daniell's of the model shown in Fig. 23. 
This enormous progress is, however, not wholly due to the superiority 
of the bichromate battery ; it is due in a great measure to the adop- 
tion of the "Universal System." 



220 TWO-LIQUID BATTERIES. 

good authority that 3000 cells are now in use at the 
General Post-office, London. 

The only new peculiarity we notice in Fuller's battery 
is the amalgamation of the zinc, which suppresses all local 
actions and prevents the waste of the zinc during the 
whole time the circuit is open. This is a capital advan- 
tage in its application to the telegraph. 

This battery appears to us to be well suited to impor- 
tant telegraph offices where the Leclanche is out of place. 
It also does very well, as Mr. Spagnoletti says, for closed 
current services. 

For ordinary telegraph offices, however, the Leclanche, 
or the chloride-of-lime battery, appears to us to be supe- 
rior. It is true that a larger number of cells is required, 
but the handling of any acid is dispensed with, and the 
battery may remain many months without being visited, 
and years without renewing the zinc. 

MILITAKY BATTEEIES. 

Bichromate-of -potash batteries with especial dispositions 
are used to set tire to military mines. A description of 
them can be found in Captain Picardat's book.* We 
will only describe two of these apparatus. 

The single-cell battery, represented by Fig. 48, is com- 
posed of a hollow zinc cylinder, in the centre of which 
is a rod of carbon. The outer surface of the zinc, which 
is not designed to effectually contribute to the useful 
action of the battery, is painted over with a black varnish, 
which shields it from the attack of the liquid. The two 
electrodes are fastened to a small circular piece of wood, 

* "Les Mines dans la Guerre de Campngne." Picardat, 1874. 



DEPOLARIZIXG-MIXTURE BATTERIES. 



221 



which is provided with terminals to which the conductors 
are attached. The liquid is contained in a glass jar closed 
with a wooden tampion surrounded with rubber. 

The electrodes are only immersed in the liquid at the 
precise moment when the mine is to be exploded, and 
they only remain a few seconds. Under these circum- 
stances the battery has its maximum effect. 

If, in a very short time after use, the electrodes can be 
washed in pure water, there will be no sensible waste of 
the zinc ; neither will any liquid have been consumed. 




Fig. 48. 



Consequently with a little care and attention the battery 
may do service a long time without being renewed or re- 
paired. The whole apparatus is enclosed in a small box 
with two compartments, which the figure plainly shows. 
This simple battery is known by the name of " Arras," 
because it was first used at the EcoU regimentaire du 
Genie $ Arras by Captain Barisien. In fact this battery 
was originally arranged as we will now describe. 

During the siege of Paris, in 1871, batteries of four 



222 TWO-LIQUID BATTEEIES. 

cells were constructed. Each cell is composed of a half 
cylinder of zinc and a half cylinder of carbon, separated 
at the upper part by a little piece of ebonite. They are 
supported by being fastened in holes made in a small 
board ; these holes may be lined with copper, which es- 
tablishes a good contact between the electrodes and the 
connections of the adjoining cells. A wooden handle 
allows the four cells to be moved at once and simulta- 
neously immersed in the jars containing the liquid. There 
was in the box a second compartment where the elec- 
trodes remain separated from the liquid while the bat- 
tery is not at work. 

We have described this apparatus to show especially 
how it may be improvized, perhaps not in the country, 
but in a besieged town or city, where there might be a 
lack of more perfect material. 

GKENET'S BOTTLE BATTEEY. 

This battery (Fig. 49) has the form of a bottle with a 
wide mouth, the lower part being almost spherical. The 
top is provided with a brass frame, to which is fastened 
an ebonite cover. To this cover are attached two carbon 
plates which permanently dip into the liquid, and which 
are held apart at the bottom by means of small pieces of 
ebonite. Between the carbon plates is suspended a zinc 
plate which may be plunged into the fluid or withdrawn 
at pleasure. The contact between the carbon and the zinc 
is prevented by little pieces of ebonite fastened to the 
carbon and which serve to guide the movement of the 
zinc. 

This battery is employed very extensively in labora- 
tories, and presents some very great advantages : 1st, 



DEPOLARIZING-MIXTURE BATTERIES. 



223 



the resistance is very slight, on account of the short dis- 
tance between the electrodes ; 2d, the waste of the zinc 
is suppressed during the intervals between experiments, 
as it is withdrawn from the liquid ; 3d, polarization is 
slackened by the comparatively large surface of the. car- 
bon electrode ; 4th, the quantity of liquid is considerable 
on account of the spherical form of the lower part of the 



bottle; 5th, and finally, the 



charging 



and 



cleaning of 




Fig. 49. 

the battery is extremely easy, as there are but a single 
jar and a single liquid. 

In spite of these advantageous dispositions, the battery 
gives a powerful current only for a short time, after which 
the intensity is seen to diminish. This element is there- 
fore only suitable for experiments of very short duration, 
such as are made in laboratories, or for surgical opera- 
tions which last but a few minutes. 

Sometimes this element is complicated by using three 



224 TWO-LIQUID BATTERIES. 

carbon plates and two zinc plates ; the surface of the 
electrodes is thus increased, and the battery still consists 
of one cell. A cell of this kind is frequently employed, 
alone or joined with others identical, to excite Rhum- 
korff's induction-coils. 

G-renet used a leaden tube starting from the cover and 
going to the bottom of the liquid. This tube served to 
introduce air into the bottle and to agitate the liquid. This 
idea has been abandoned in ordinary practice, although it 
possessed great merits. 

Although this be an element with no porous partition, 
it is sometimes wrongly called a single-liquid cell ; there 
are in reality two liquids mixed; viz., sulphuric acid 
designed to act upon the zinc, and a mixture of acid and 
bichromate intended to depolarize the carbon. 

TKOUVE'S BATTERY. 

This battery, represented by Fig. 50, is a derivative of 
the preceding one. A certain number of zinc and carbon 
plates are placed in a suitable ebonite frame, and are held 
at short and equal distances apart, in such a manner as to 
be joined to form either a single element with a large 
surface or two elements with a smaller surface which are 
joined in intensity. 

The frame or box in which the plates are placed is 
formed of an ebonite base and two vertical ebonite sup- 
ports, N, united and held at the top by the handle, A. The 
distances between the plates are maintained by bands of 
rubber placed around the carbons horizontally. In case 
of any accidental shaking these rubber bands deaden the 
shock, which is very important for the carbons, as their 
fragility is such as to necessitate great care to prevent 



DEPOLARIZING-MIXTTTRE BATTERIES. 



22o 



their being broken. Metallic and movable clamps are 
placed upon the zinc and carbon plates, and are attached 
to cross-pieces above, which join several zinc or carbon 
plates together. 

In the figure, to the right, in front, are seen three car- 
bon plates joined together ; this is the positive pole of the 




Fig. 50. 

battery. The three corresponding zinc plates are behind, 
joined to each other and to three other carbon plates; finally, 
the last three zinc plates are united to the left, in front, and 
this forms the negative pole of the battery, which is thus 
composed of two cells joined in intensity. 

The two cells are immersed in a single trough contain- 



226 TWO-LIQUID BATTERIES. 

ing the liquid, or rather the mixture. There is, to be sure, 
a certain loss of current by the liquids, but the simplicity 
of the battery more than compensates for the fault in 
question. 

A tube, T, permits the introduction of air, which goes 
to the bottom of the liquid, agitates it, and contributes to 
the depolarization. The battery may be shaken in the 
liquid by means of the handle, which will produce almost 
the same effect as the injection of the air. 

It is seen from the preceding that Trouve's arrange- 
ment presents the following advantages : 

1. The battery can be easily and rapidly dismounted, a 
convenience wanting in Grenet's element. 

2. The plates, when dismounted, can be conveniently 
washed, which prevents any slow waste caused by the acids. 

3. The zinc plates can be reamalgamated, and when 
worn can be replaced without the help of a special con- 
structor. 

4. The clamps washed and dried may serve indefinitely. 
Finally, the battery may be so arranged as to form two 

or more elements, or a single cell. 

BYRNE'S PNEUMATIC BATTERY. 

Dr. Byrne, of Brooklyn, New York, has invented, upon 
the preceding principles, a battery which attracted a great 
deal of attention in .1878, and which deserves to be dwelt 
upon. 

The positive electrode is formed of a plate of zinc and 
placed between the two negative electrodes, as in Grenet's 
battery. 

The double negative electrode is in reality a very thin 
plate of platinum. But Dr. Byrne, taking into account 
the insufficient conductibility of this thin plate, faced one 



DEPOLARIZING-MIXTURE BATTERIES. 227 

side of it with a plate of copper. Moreover, to avoid the 
attack upon the copper, lie coated it with lead. Thus 
the electrode consists of a copper plate which is coated 
with lead, and which has one side faced with a plate of 
platinum. A layer of varnish protects the parts of the 
lead which are not covered by the platinum. 

The element is placed in a large square ebonite jar, 
provided with a cover of the same material, to which the 
two negative electrodes are attached. Between them is 
suspended the zinc plate, which may be immersed in the 
liquid or taken out when the battery is not at work. 

Finally, Dr. Byrne affixed to his battery a means of 
aerating or agitating the liquid. This apparatus consists 
of a perforated rubber tube, which is fixed in the bottom 
of each cell, and through which air can be forced into the 
solution by means of a fan or blower ; this is what Grenet 
did as early as 1857. 

The intensity of the current furnished by this element 
is considerable ; it is especially suited to medical uses, and 
particularly to cautery purposes. 

With a battery of 10 cells a stout platinum wire, 30 
inches long and 1|- inches in diameter, was brought to a 
glowing red heat. 

The advantage of the injection of air is shown by the 
fact that when air is being forced in the platinum wire is 
quickly brought to a glowing red heat, and that on ceas- 
ing to inject air the wire gradually cools down. 

The electro-motive force of this element varies but 
slightly (from 1.73 to 1.97), as will be seen further on ; 
but its variable resistance (from 0.78 to 0.14 ohm) is al- 
ways exceedingly small. 

This feeble resistance is the result of several circum- 
stances : 



228 TWO-LIQUID BATTERIES. 

1. The nature of the negative electrode, which is very 
well combined, and is superior to the carbon electrode. 

2. The great conductibility of the liquid, which is very 
rich in sulphuric acid. 

3. The high temperature which is produced when the 
circuit is closed and air injected. 

AGITATION OF THE LIQUID. 

' "We have already spoken of the advantage of agitating 
the liquid or the electrodes of a battery subject to polari- 
zation. The result is a freeing of hydrogen bubbles 
which diminishes the polarization. It happens also, some- 
times, that precipitates possessing little conductibility 
form themselves upon the conducting electrodes, and 
which the agitation causes to fall to the bottom of the jar. 

This latter impediment is met with in the bichromate 
battery; it happens in certain instances that there is 
formed, besides the chrome alum, a yellow precipitate 
which partially covers the carbon and diminishes the in- 
tensity of the battery. 

From the beginning, Grenet, to whom is due the very 
excellent form of the element that we have made known, 
arranged a tube of lead descending to the bottom of the 
liquid ; to this tube was fastened another one of rubber, 
through which air was injected," either by blowing with 
the mouth or with a bellows. This air passed through 
the liquid from top to bottom, agitated it and depolarized 
the battery : at least that is what it was believed to do at 
the time. 

Preece has lately made some very extensive experiments 
upon the effect of the injection of air in Byrne's battery, 
which have given fresh interest to the subject. 



BEPOLARIZING-MIXTIjRE BATTERIES. 220 

Lacld announced that by introducing successively into 
the battery common air, oxygen, and hydrogen-, no differ- 
ence was observed. Preece confirmed the truth of this 
statement, and obtained the same effects by injecting a 
liquid into the liquid. It is therefore well established that 
the air does not act chemically, but purely by the agitation 
it produces. 

Preece has also established that the electro-motive force, 
though not invariable, varies but very little, the limits being 
1.73 and 1.97. The result is that the cause of the change 
in the intensity of the current is not depolarization in the 
ordinary sense of the word. 

His experiments have proved, moreover, that the inter- 
nal resistance of the battery varies considerably as the 
temperature of the liquid is increased under the influence 
of the agitation. 

This is shown by the subjoined table : 

Electro-motive 
Temperature. Force. Resistance. 

Fahr. Centig. (Daniell=l.) (Ohm = l.) 

80 26.66 1.73 0.78 

100 37.77 1.88 0.61 

120 48.88 1.92 0.35 

140 60.00 1.97 0.24 

160 71.11 1.97 0.19 

180 82.22 1.97 0.17 

200 93.33 1.97 0.14 

In order to further elucidate the question, Preece sub- 
mitted the liquid to a direct experiment, outside of the bat- 
tery and away from the zinc ; he employed two platinum 
electrodes, as is almost always done when the resistance 
of liquids is to be ascertained, and he found the f ollowing 
figures : 



230 TWO-LIQUID BATTERIES. 

Temperature. 

Fahr. Centig. Resistance in Ohms. 

70 21.11 1.78 

90 32.22 1.50 

110 43.33 . 1.37 

130 54.44 1.15 

150 65.55 1.00 

170 76.66 0.79 

190 88.88 0.43 

210 99.99 0.20 

212 (boiling point) 0.04 (variable) 

But the high temperature is not developed by the ac- 
tion alone of the acid upon the bichromate of potash ; the 
zinc must necessarily be present. One is led to the belief 
that the circulation of the liquid promoted by the air 
tends continually to bring fresh acid in contact with the 
zinc plate and to disperse the salt formed at its surface, 
which would obstruct further action of the acid. 

This circulation of the liquid is especially necessary to 
cause a renewal of the contact (between the liquid and the 
positive electrode) when the electrodes are very near each 
other, as is the case in the batteries of Grenet, of Trouve, 
and of Byrne, because in this latter instance the natural 
motion of the liquids is slower and more difficult. 

Other inventors, seeing the utility of the agitation in 
the liquid, have sought to improve upon the process sug- 
gested by Grenet. They have (first Chutaux and then 
Camacho) arranged several elements in gradation, the 
liquids flowing from one to the other and thereby pro- 
ducing a renewal of the active fluid at the contact with 
the electrodes. 



DEPOLARIZIXG-MIXTUEE BATTERIES. 



231 



CAMACHO'S BATTERY. 

We have said above that Chutaux sought to produce 
the agitation of the liquids which is so advantageous in 




Fig. 51. 



the bichromate-of -potash battery, by placing the cells one 
above the other and causing the liquid to pass succes- 



232 TWO-LiQUID BATTERIES. 

sively in two or three cells. This disposition appears to 
ns very cumbersome, and we prefer that of Camacho, 
represented by Fig. 51. 

The jars are placed in gradation upon steps ; the liquid 
falls from a special reservoir into the porous jar of the 
top cell, whence it is carried by means of a siphon into 
the succeeding one, and so on. 

The negative electrode consists of a small bar of carbon 
and a considerable mass of crushed gas-retort carbon, 
which fills the porous jar ; the enormous surface of this 
electrode renders polarization very slow. 

We have recommended this disposition for all batteries 
subject to polarization, that is for those which have not 
an absolutely efficient depolarizing agent. In this battery 
it is very advantageously applied. Gaugain has published 
tables of comparison, which show the influence of crushed 
carbon placed around the principal plate. 

DELAUKIER'S BATTERY. 

This is a modification of the bichromate-of-potash 
battery. It has in the outer jar a zinc electrode which 
surrounds the porous jar, in which is a carbon electrode. 
"When the battery is charged, pure water is put with the 
zinc, and with the carbon a liquid composed of water, 
bichromate of potash, sulphate of soda, sulphate of iron, 
and sulphuric acid. 

At first starting the resistance is considerable on account 
of the pure water in the outer jar ; but a certain quantity 
of the compound liquid soon passes through the pores of 
the diaphragm and the resistance of the element diminishes 
about one half. 

It is difficult to ascertain precisely what chemical 



BEPOLAEIZIXG-MIXTtTEE BATTEUIES. 233 

actions take place between these numerous compounds, 
either while the circuit is open or closed. However, 
Delaurier's battery is employed by many, and especially 
for depositing silver, for depositing nickel, gilding, etc. 

The advantages of this battery are mostly attributed to 
the proportions of its different parts. The porous jar is 
comparatively large and contains two carbon plates instead 
of one, which diminishes the internal resistance. 



PART III. 
VARIOUS BATTERIES. 



DEY PILES. 



We will briefly describe those galvanic batteries called 
dry piles, in which the liquid is replaced by a slightly 
moistened or oily siibstance. 

In reality, these batteries are not dry, and cease to work 
when they are thoroughly dried. In the beginning, cells 
were formed of two thin plates of copper and of zinc, 
having between them a sheet of paper saturated with oil 
or salt water and nearly dry. 

In 1812 Zamboni suggested a more original disposition, 
which has been but slightly modified, and which is con- 
structed as follows : 

A sheet of paper is turned upon one side, and upon the 
other side is spread witli a small brush a thin layer of 
peroxide of manganese thinned with milk or with gummy 
water, or even with common paste ; this is left to dry, 
and then, placing a certain number of these sheets one 
upon another, small discs about 1^ in. in diameter are cut 
out by means of a punch ; the discs are then placed one 
upon another in regular order. To render this pile of 
discs solid, the latter are placed in a glass tube well var- 
nished on the inside ; they are pressed down as tightly as 
possible, in order to insure good contact. At both ends 



236 VARIOUS BATTERIES. 

there are metallic plates which represent the poles of the 
battery. These metallic plates are a little larger in diam- 
eter than the discs of the battery and are pierced with 
several holes, through which silk cords are passed which 
hold the compressed column and even dispense with the 
glass tube of which we have spoken. 

Great care must be taken, especially when the glass 
tube is not used, to exclude the air, which may be done 
by covering the pile with gum lac or with sulphur ; other- 
wise losses would be sustained on account of the humidity 
of the air, and the effects of the battery would be greatly 
lessened. 

. Electric sparks can be produced with these batteries, as 
their electro-motive force is considerable on account of 
the large number of elements which enter into their 
composition. 

The internal resistance of these batteries is enormous, 
as is easily understood. This explains why a most sensi- 
tive galvanometer is needed to detect any current. 

It is easy to comprehend how dry jnles recover but 
slowly their charge, after having been discharged, and 
how they do not receive their maximum charge in a damp 
atmosphere. 

Zamboni's batteries do not last forever; it has been 
proved that after a few years they lose all their force. 
In their last stages of weakness, a portion of their energy 
may be restored by exposing them to. an intense heat. 
It is probable that the chemical actions are thus accel- 
erated. 

The chemical reaction which takes place in each element 
is very simple ; the peroxide of manganese is decomposed 
and the tin is oxidized at its expense. It is to be noted 
that the bioxide plays the part of both conducting electrode 



VARIOUS BATTERIES. 237 

and of active substance. The paper acts as simple con- 
ductor, which property it owes to the humidity it con- 
tains. When this humidity disappears, the battery no 
longer produces any electricity, and it is only necessary 
to expose it to damp air in order that it may recover its 
electro-motive properties. Experiments show that dry 
piles possess all the properties of ordinary batteries. 

Dry piles used to be employed to turn small apparatus 
based upon the attraction and repulsion of electrified 
bodies. Perpetual motion was thought to have been 
secured, but after a few years these apparatus stopped, 
proving once more the folly of such a research after the 
impossible. These scientific playthings have now gone out 
of fashion ; no more are constructed, but they are found 
described and illustrated in nearly all works upon physics. 

To-day dry piles are only used in connection with 
electroscopes, notably with that of Bohnenberger, the 
description of which is found in most works treating of 
the subject. 

IDENTICAL ELECTKODE BATTEEIES. 

Hitherto in batteries we have always met with two 
distinct electrodes immersed in one or two liquids. 

We desire to show that batteries may be composed 
which contain identical electrodes, provided these elec- 
trodes be immersed in two different liquids. The direc- 
tion of the current will be determined because one of the 
liquids will attack its electrode more actively and the other 
will attack its electrode less actively or not at all. 

We will give a very simple example. In a jar put a 
saturated solution of sulphate of copper, and on top of this 
some acidulated water, or salt water, or pure water. Now 



238 VARIOUS BATTERIES. 

if a copper plate be placed on end in this liquid, it will be 
attacked at the top and become charged with copper at 
the bottom. It is plain that we have there an element of 
copper, acidulated water, sulphate of copper, and copper. 

This experiment furnishes the explanation of how a 
drop of sulphate of copper thrown npon copper will p*o- 
duce an attack, the same as a drop of nitrate of silver upon 
a silver plate. It happens that, by difference of specific 
gravity, the more saturated solution falls to the bottom 
and the less charged solution rises to the top ; conse- 
quently a current is produced which transfers the metal 
from one point to another. In order .to have no action 
at all, the composition of the liquid ought to be the same 
throughout. 

We thought it better to note these observations to show 
the reader that various phenomena not apparently electric 
can in reality only be explained by electro-chemistry. 

UNATTACKED ELECTEODES IN BATTEEIES. 

In all the batteries hitherto described we have found a 
metallic generating electrode. This electrode is dissolved 
in the liquid in which it is immersed, and this action pro- 
duces a current. But the actions between liquids can 
also produce electricity. 

If in a vessel divided into two compartments by a 
porous partition acid is put in one division and an alka- 
line solution in the other, there will be a reciprocal reac- 
tion in the pores of the diaphragm and the formation of 
a salt ; if two platinum plates be immersed in the liquids 
a current will be made manifest in a wire conductor 
uniting the two plates. The positive pole of this element 
will correspond to the acid. Nothing would be changed 



VARIOUS BATTERIES. 239 

if, instead of two platinum plates immersed in the two 
compartments, there were one of platinum and one of 
gold. Neither of them are attacked, both are conducting 
electrodes, and there is in reality no generating electrode. 
We will not insist upon these voltaic contrivances 
which have as yet received no application. It should be 
noticed, however, that they generally polarize like 
ordinary batteries. A single one has been invented 
which does not polarize, and which should be noted in 
the enumeration that we have undertaken. 

BECQUEKEL'S OXYGEN-GAS BATTEEY. 

This* apparatus is composed as follows : A glass tube 
closed at the bottom by a porous partition is placed in a 
flask containing nitric acid ; potash is poured in the glass 
tube, and in each liquid is placed a bar of platinum to 
which a conductor is attached. When the circuit is 
closed by bringing the two connections in contact with 
each other, a lively action takes place, the acid and the 
base combine. But this simple reaction does not take 
place alone ; the current thus produced decomposes the 
surrounding water, the hydrogen goes to the nitric acid, 
which it reduces, and is not given off upon the electrode ; 
consequently there is no polarization. The oxygen goes 
to the potash, remaining free, and surrounds the plati- 
num plate. 

This battery is remarkable as being the only one in 
which oxygen is evolved, the contrary from all other 
batteries in which hydrogen is evolved (except, of course, 
totally depolarized batteries). 

It moreover possesses a great historical interest, be- 
cause it is the first battery furnishing a constant current 



240 VARIOUS BATTERIES. 

that was constructed ; it is in this element that were first 
employed two liquids and a porous diaphragm. 

COKE-CONSUMING BATTERY. 

Throughout this work we have shown that the com- 
bustion or dissolving of zinc is the principal and almost 
only means employed to produce voltaic electricity. 
Thus, each equivalent of electricity costs, at the mini- 
mum, one equivalent of zinc plus an equivalent of one 
or two other substances, and it is for that reason that 
electricity is so expensive. 

. It might be reasonably inquired whether the combus- 
tion of common coal could not be utilized for the produc- 
tion of electric currents. 

Magneto-electrical machines, which furnish a continu- 
ous current, and of which, the Gramme machine is the 
model, present a solution of this problem. When a 
Gramme machine is put into motion by a steam motor, 
there is seen a transformation into electricity of the heat 
produced by the combustion of the coal in the furnace of 
the motor. That is an indirect solution, for the heat is 
first transformed into motive force, which is in turn 
transformed into electricity ; but it is a very good solu- 
tion, and is to-day confirmed by practice. If the elec- 
tricity produced by Gramme machines cost but little, it 
is because it is produced by the combustion of coal, which 
is as yet the most advantageous source of energy discov- 
ered — an energy which presents itself in the form of 
heat, of chemical energy, of movement, or of electricity, 
and which may be transformed into one or the other of 
these four powers. 

It is very probable that a direct transformation into 



VAKIOUS BATTEKIES. 241 

electricity of tlie lieat produced by the combustion of 
coal may be obtained. Mr. Jabloclikoff lias already in- 
vented a battery cell which fulfils the above conditions. 

The liquid of this cell is melted nitrate of potash or 
nitrate of soda ; one electrode is of coke, and the other 
of platinum, or even of cast-iron. The coke is burned at 
the expense of the oxygen of the nitrate, and produces 
torrents of carbonic acid; the cast-iron remains unat- 
tacked. 

The coke is therefore the positive electrode, and the 
cast-iron the negative. It is the contrary of that which 
would take place in a battery with an ordinary liquid, 
acid, or salt dissolved in water. 

The nitrate should be previously melted, but as soon as 
the action begins the salt remains liquid on account of 
the great heat produced by the combinations which take 
place ; and if the element be left to itself it suffices, to 
put it in action, to bring the end of the coke to a glowing 
red heat, and then to press it against the surface of the 
salt ; the chemical action begins immediately, and by the 
heat it produces the melting of the nitrate, and soon the 
element is reproduced. 

It might be found that such a battery cell presents 
nothing practical in its actual form, and we do not hesi- 
tate to express that opinion, but we believe that it points 
out a new way in which much progress might be made 
if the attention of physicists were turned in that direc- 
tion. Yolta's battery itself when invented was a purely 
scientific novelty, and it was far from being regarded as 
an object of any practical utility. 

Mr. Jabloclikoff' s experiment will doubtless call forth 
many commentaries. This is not the place for any re- 
marks upon the subject. We only wished, in mention- 



242 VARIOUS BATTERIES. 

ing this battery cell, to show our readers that beyond the 
already explored horizons there " remain other worlds to 
discover and virgin lands to cnltivate. 

GAS BATTERIES. 

. We have explained how a voltameter, in which oxygen 
and hydrogen were evolved, could become a source of 
electricity. To show this, it is only necessary to attach 
the wires of a galvanometer to the terminals of a vol- 
tameter thus charged. 

If the electrodes of the voltameter are immersed partly 
in the acidulated water and partly in the previously 
evolved gases, the voltameter may furnish a current 
during a considerable length of time ; the oxygen and 
hydrogen recombine through the liquid, and the current 
resulting from this combination lasts as long as there is 
any gas in contact with one or the other of the elec- 
trodes. 

Under these circumstances, a voltameter becomes in 
reality a gas battery. "When the gases are consumed 
they can be replaced, and the action of the battery pro- 
longed, just as acids or salts are renewed in ordinary 
batteries. 

Grove, to whom is due the invention of these interest- 
ing contrivances, has given to them many and various 
forms. He has also substituted for the oxygen and the 
hydrogen other gases, such as chlorine, protoxide of car- 
bon, bioxide of nitrogen, oleiiant gas, and has found bat- 
teries analogous to the first one. He has discovered that 
certain gases when taken together produce no electric 
current ; viz., nitrogen and oxygen, nitrogen and hydro- 
gen, protoxide of nitrogen and oxygen. 



VARIOUS BATTERIES. 243 

A certain number of cells, such as we have described, 
may be joined in intensity, and it will be seen that they 
possess the same general properties as ordinary batteries. 

Gaugain has established the fact that gas batteries do 
not act except by dissolved gases ; so that their force be- 
comes less as the solution weakens, just as in sul'phate-of- 
mercury and sulphate-of-lead cells. 

It is moreover probable that, in addition to this special 
weakening, gas batteries are liable to polarize like the 
others, especially when there are several elements in the 
circuit. 

Batteries in which only one of the active bodies is 
gaseous, while the other is liquid, have also been dis- 
covered. 

Thus Grove has been able to obtain a current by caus- 
ing oxygen to act upon sulphate of protoxide of iron, 
which is subject to oxidation and is transformed into 
sulphate of peroxide, or by causing hydrogen to act upon 
nitric acid, which decomposes and gives oif oxygen. 

Ed. Becquerel caused hydrogen to act upon chloride of 
gold in the presence of platinum. 

Two or single gas batteries can receive no application; 
the great interest they possess is simply theoretical. 

. SECOND AKY BATTERIES. 

We have already said that a voltameter submitted to 
the influence of an electric current for a moment be- 
comes capable of furnishing a current contrary to the ex- 
citing current. This capital fact has enabled us to show, 
under one of its plainest forms, the phenomenon of the 
polarization of electrodes. 

The current thus furnished by the voltameter is a sec- 



244 VARIOUS BATTERIES. 

ondary current, and the apparatus becomes a secondary 
element. The current may be said to have been fur- 
nished by the battery, and returned by the secondary 
element. 

The study of this question dates from the beginning 
of the present century — Gautherot in 1801, and soon 
after Hitter called attention to it. Hitter has shown 
that secondary elements may be produced under other 
forms than that of the voltameter ; two electrodes of 
platinum, of carbon, of copper, or indeed of more easily 
oxidized metals, placed in a conducting liquid, suffice to 
constitute a secondary element. 

A column battery formed of a succession of discs of 
copper and cloth moistened with sulphate of potash con- 
stitutes a secondary battery. 

Pursuing the general idea with which this work has 
been written, we can, in conclusion, do no better than to 
study in detail secondary batteries, which present an 
application of the polarization of electrodes. 

To make the subject clear, let us consider a secondary 
battery formed of two platinum plates immersed in acidu- 
lated water. 

The most feeble current suffices to polarize these elec- 
trodes, as can be shown by carefully observing the sec- 
ondary current. It is not necessary that the exciting 
current should have a tension sufficiently great to decom- 
pose water ; one of Daniell's elements, or even a more 
feeble one, can polarize the secondary element. 

"When the cell is polarized by a more energetic current, 
the secondary current also increases in energy, but it is 
clear that the electro-motive force of the second can never 
be superior to that of the first. 

If in a circuit are placed an ordinary cell, a galvanoine- 



VAKIOUS BATTEEIES. 



245 



ter, and a secondary cell, the following facts are ob- 
served : at first the current of the polarizing cell passes 
with great energy, as the .galvanometer shows, then it 
gradually diminishes on account of the increasing polari- 
zation of the secondary cell. 

If the polarizing current is not sufficient to decompose 
water— if, for instance, it is furnished by one of Daniell's 
cells — it happens that the secondary current counterbal- 




Fig. 52 



ances the principal current, as shown by the galvanome- 
ter, which marks no deflection. 

If the principal current is sufficient to decompose 
water, the above equality is never reached, and the free- 
ing of gases corresponds indefinitely to a circulation of 
the current made manifest by the galvanometer. 

If, instead of a single secondary element, several are 
placed in the circuit, polarization will be divided between 
them ; each one taken separately will furnish a secondary 
current after being a moment under the influence of the 
principal current, but the sum of the electro-motive forces 



246 



VARIOUS BATTERIES. 



of these secondary currents can never become superior to 
that of the polarizing current. 

But it* these secondary cells be charged separately and 
then joined in intensity, the total current might have a 




w 1 Mtrgt 



Fig. 53. 



considerable energy and be superior to that of the princi- 
pal current by which they have been successively ex- 
cited. 



VARIOUS BATTERIES. 247 

All this will be made clearer by the following detailed 
study of secondary cells having electrodes of lead. 

As early as 1859 Mr. Plante showed that lead was the 
most favorable metal for use in secondary batteries, and 
he has since that time accumulated many proofs of this 
superiority. Figs. 52 and 53 show the element as con- 
structed to-day. In a tall vessel made of glass, of rubber, 
or of ebonite are placed two sheets of lead rolled to- 
gether parallel to each other, and kept apart by two 
strips of rubber rolled with them ; these two sheets are 
immersed in a solution containing one tenth of sulphuric 
acid. The vessel is closed by a sealed stopper in which 
there is a hole through which the liquid is introduced 
and extracted, and through which the gases evolved dur- 
ing the charging may pass off. The apparatus is capped 
by an ebonite cover furnished with two clamp screws 
which communicate with the two electrodes ; there are 
also two clamps, which hold metallic wires to be heated 
,and melted by the secondary current. 

To charge this secondary element to its maximum, two of 
Bunsen's cells or three of Daniell's must be used. During 
the charging, one of the electrodes becomes oxidized, a 
brownish layer of peroxide of lead is soon seen, and the 
metallic aspect completely disappears ; the other electrode 
only changes in appearance, its surface becoming covered 
with a grayish matter. 

"When it is charged to its maximum — that is, when oxy- 
gen begins to free itself from the brown electrode — it is 
well to separate the secondary cell from the active battery, 
as the polarizing current is no longer useful and is wasted. 

The secondary element thus charged and left to itself 
can preserve a part of its charge several days, and at the 
end of a week it is still far from being exhausted. 



248 VARIOUS BATTERIES. 

The secondary cell when charged to its maximum has 
an electro-motive force equal to one and a half that of 
Bunsen's cell ; it can bring to a glowing red heat a platinum 
wire large or small according to the dimensions of 
the cell, or, better, according to the size of its electrodes. 
It can be easily understood, indeed, that the quantity of 
electricity furnished by the apparatus is in proportion to 
the extent of surface of the lead submitted to the action 
of the polarizing current and covered with an active elec- 
tro-chemical deposit. 

It should be noted that the peculiar form of the elec- 
trodes offers a large surface and a small resistance" under 
a small volume ; so that one of Planters secondary cells is 
equal to an active or ordinary cell of extraordinary dimen- 
sions ; the small model has a surface of eight square 
decimetres, the large one a surface of four square deci- 
metres. 

The current furnished by a secondary element can 
produce chemical decompositions, act upon an electro^ 
magnet, etc. ; but if its intensity be measured in one way 
01 another, with a galvanometer for instance, it is seen to 
diminish from the maximum of which we have spoken 
above. This decrease is very slow if the circuit offers a 
great resistance, and if, as a consequence, there is a very 
small flow of electricity ; it is on the contrary very rapid 
if the circuit offers but a slight resistance, because the 
electricity flows in a large quantity. 

A very curious and interesting fact is noticed during 
the discharge of the cell ; it is apparently completely dis- 
charged, but if the circuit be left open several minutes, 
it has been ascertained that it recovers a certain energy 
and that it can still furnish a certain quantity of elec- 
tricity. 



VARIOUS BATTERIES. 249 

The battery thus delivered of its first residue and left 
to itself for some time will furnish a second residue, less, 
of course, than the first. And this is not the last one, for 
several more can be obtained. Mr. Plante has very 
clearly explained this peculiarity. The secondary element, 
when it becomes active, discharges itself and at the same 
time polarizes, as all single-liquid batteries. This polari- 
zation attains in a certain time a force almost equal to 
that of the already weakened secondary element, and the 
action ceases or is reduced to very little. If the battery 
then be left to rest, it depolarizes as do all single-liquid 
batteries polarized by their own action. As soon as the 
battery is depolarized it is again ready to furnish a cur- 
rent, but during this new discharge it again polarizes, 
and so on. 

If we consider the secondary cell as completely or 
almost completely discharged, it may be recharged with 
two of Bunsen's elements, as in the first instance ; but it 
is well to note that the more immediately after the dis- 
charge the new charge be given, the more rapidly it may 
be given. 

Moreover, the greater number of times a secondary 
element is charged and discharged, the better it is. In 
the beginning, when it is nearly new, there is an advan- 
tage in polarizing the electrodes, first in one direction 
and then in the other, and in reversing several times the 
direction of the charge ; but when the element is formed, 
great care must be taken to always charge it in the same 
direction. If this precaution be neglected it will take a 
much longer time to charge it, for the oxide of lead, which 
may still remain upon one of the electrodes, must be re- 
duced and the previously negative plate oxidized. But 
after this operation the secondary cell will have recovered 



250 



VARIOUS BATTERIES. 



all its qualities : it may indeed be said to have gained 



some. 




Fig. 54. 



Fig. 54 shows a peculiar form given to the secondary 
element by Mr. Plante, and which he has called Saturn's 
tinder-box. At the top are seen two clamps which hold a 

platinum wire stretched 
between them ; each time 
that, by pressing with the 
finger, the two springs at 
the bottom are brought 
into contact the battery 
sends a current through 
the platinum wire, which 
is thereby brought to a 
glowing red heat, whence 
follows an almost instan- 
taneous lighting of the 
candle. With one of these contrivances the candle may 
be lighted one hundred times, and it is only after these 
frequent lightings that it has to be recharged with three 
of Daniell's cells. That is a means of obtaining fire and 
a very economical means too, for the secondary element 
spends nothing and the charging battery consumes but a 
few grammes of sulphate of cop|)er for a prolonged 
working of the tinder-box. 

This same apparatus can be used to touch off mines 
either in civil or military service ; the experiment shows 
that with fine platinum-wire fuses (j^-q of an inch) 
combustion may be obtained through a copper wire 1000 
yards long. 

With a contrivance of this kind- surgeons may cauterize 
a wound, and it has frequently been applied in that 
way. A secondary element is much more easily trans- 



VARIOUS BATTERIES. 



251 



ported into a hospital or to the house of a sick person 
than active cells which it may replace. 

Finally, secondary cells can be joined in quantity or in 
intensity and constitute batteries capable of producing all 
the effects of the most powerful ordinary batteries. 
Fig. 55 represents the secondary battery as disposed by 
Mr. Plante. 

The number and dimensions of the cells can be varied 
according to the tension and quantity desired. Here there 




Fig. 55. 

are twenty elements arranged in two rows. At the top 
there is a very conveniently disposed commutator, which, 
in one position, joins the cells in quantity; in another 
position, at right angles with the first, it joins them in 
intensity. In the first position all the outer electrodes 
are joined to one metallic strip, and all the inner elec- 
trodes to another metallic strip, so that the whole arrange- 
ment represents a single cell with a large surface. It is 
in this condition that the charge is made ; two of Bun- 
sen's cells are sufficient, and they complete the charge in 



252 VARIOUS BATTERIES. 

a longer or shorter time, according to the dimensions of 
the cells and to the extent of the surface of the lead to 
be polarized. In the second position the outer electrode 
of each cell is put into communication with the inner 
one of the following cell, and the apparatus becomes a 
real battery of twenty cells. It is in this condition that 
the battery is discharged, and it is equal, at first starting, 
to 30 of Bunsen's very large cells. 

As the battery is being discharged the tension dimin- 
ishes, as we explained when speaking of the single sec- 
ondary element. If it takes one minute to charge the 
battery of secondary cells in quantity, it cannot be expected 
that the discharge of the cells in intensity will furnish the 
same effects as 30 of Bunsen's of the same size during a 
longer period than four seconds, for the apparatus fur- 
nishes no electricity and can only transform that which 
has been given to it. Mr. Plante has made some exact 
experiments in this direction, and has found that in this 
transformation about one tenth is lost, or, in other words, 
the machine returns nine tenths of that which was given 
to it. 

It is clearly seen that the secondary battery can only 
produce effects of very short duration, but in most cases 
this is all that is neccesary. 

If, for instance, a large number of mines are to be 
simultaneously exploded by means of fuses of fine wire, it 
may be done by placing all the fuses in divided circuits 
and by causing the current of the secondary battery to 
pass through them all at once. This manner of proceding 
is very economical, and it is certainly less laborious and 
costly to mount two of Bunsen's cells and to charge a 
Becondary battery than to charge 20 or 30 of Bunsen's 
elements, especially when the battery is only worked a 
few seconds and only four or five times during a day. 



TABLES, 



253 



I. ELECTRIC CONDUCTING POWER OF SOLIDS. 
{Ed. Becquerel. — Annales de Chimle et de Physique, 1846.) 



Substances. 


Metal 
(hard drawn). 


Metal 
(annealed). 


Silver, pure (reduced from the chloride) 


93.448 
89.048 
64.385 
24.574 
24.164 
13.656 
13.977 
12.124 
8.245 
8.042 
1.8017 


100.000 - 
91.439 




65.458 


Cadmium 




Zinc 




Tin 




Palladium 




Iron 


12.246 


Lead . 




Platinum 


8.147 


Mercury at 14° centig 









Substances. 


Conduc 
0° Centig. 


tivity at 
100° Centig. 


Coefficient 

for 
1° Centig. 


Silver, annealed 


100. 

91.517 

64.960 

24.579 

24.063 

14.014 

12.350 

8.277 

7.933 

1.7387 


71.316 
64.919 
48.489 
17.506 
17.596 
8.657 
8.387 
5.761 
6.688 
1.5749 


0.004022 




0.004097 


Gold...:::::::::::::::::::::::::;:::::::::::; 


0. 00*397 




0.004040 


Zinc 


0.003675 


Tin 


0.006188 


Iron, annealed 


0.004726 


Lead 


0.004349 


Platinum, annealed 


0.001861 


Mercury, distilled 


0.001040 







254 



TABLES. 



II. SPECIFIC RESISTANCES DETERMINED 
MATTHIESEN. 



BY 



yiable taken from Fleeming Jenkin.) 



Names op Metals. 



«"d S 


CD &fl CD 


£ g--> 


iSfl 


fe «8 


££0 


o3 «-£ 


^ CD 


°ce.§ . 




PP 


tance 
erne 
ighi 
mme. 


esis 
one 
one 
dia 


M p| CD 03 


« 


« 


Ohms. 


. Ohms. 


0.01937 


0.1544 


0.02103 


0.1680 


0.02057 


0.1440 


0.02104 


0.1469 


0.02650 


0.4080 


0.02697 


0.4150 


0.03751 


0.0757 


0.07244 


0.4067 


0.1166 


1.96 


0.1251 


0.7654 


0.1604 


1.071 


0.1701 


0.9738 


0.2526 


2.257 


0.4571 


2.411 


1.689 


13.03 


1.2247 


13.06 


0.3140 


. 2.959 


0.2695 


1.85 


0.1399 


1.668 



$QfiD 



Silver, annealed 

Silver, hard drawn — 

Copper, annealed 

Copper, hard drawn . . 

Gold, annealed 

Gold, hard drawn 

Aluminium, annealed 

Zinc, pressed 

Platinum, annealed . . 

Iron, annealed 

Nickel, annealed 

Tin, pressed 

Lead, pressed 

Antimony, 

Bismuth, pressed 

Mercury, liquid — 

Platinum silver 

German silver, hard or an- (_ 
nealed i 

Gold - silver alloy, hard or ) 
annealed : two parts gold, '- 
one part silver ) 



Microhms. 

1.521 
1.652 
1.616 
1.(52 
2.081 
2.118 
2.945 
5.689 
9.158 
9.825 

12.60 

13.36 

19.85 

35.90 
132.7 

99.74 

24.66 

21.17 



10.99 



Ohms. 

9.151 

9.936 
9.718 
9.940 
12.52 
12.74 
17.72 
34.22 
55.09 
59.10 
75.78 
80.36 

119.39 

216 

798 

578.6 

148.35 

127.32 
66.10 



Ohms. 

.2214 
.2415 
.2064 
.2106 
.5849 
.5950 
.1085 
.5831 
2.810 
1.097 
1.535 
1.396 
3.236 
3.456 
18.64 
18.72 
4.243 

2.652 





Resistance of one cu- 
bic centimetre be- 
tween opposed 
faces, expressed 
in microhms. 


Temperature, 
Centigrade. 


Graphite specimen, No. 1 

No. 2 -. 

" • " No. 3 


2,390 

3,780 

41,800 

4,280 

67,200 

212,500 

132 ohms 


22° 
22° 

22° 




25° 




26.2° 




19.6 




20° 







TABLES. 



255 



III. CONDUCTIVITY OF LIQUIDS. 

(Ed. Becquerel. — Annates de Chimie et de Physique, June 1846.) 



Substances. 



Silver 

Sulphate of copper, satu- 
rated 

Sulphate of copper, di- 
luted to half 

Sulphate of copper, di- 
luted to quarter 

Chloride 01 sodium, satu- 
rated 

Chloride of sodium, di- 
luted to half 

Chloride of sodium, di- 
luted to third 

Chloride of sodium, di- 
luted to quarter 

Bichloride of copper, sat- 
urated and diluted with 
five times its bulk of 
water 

Nitrate of copper, satu- 
rated 

Nitrate of copper, diluted 
to § 

Nitrate of copper, diluted 
to half 

Nitrate of copper, diluted 
to quarter 

Sulphate of zinc, saturated 

Sulphate of zinc, diluted 
to half 

Sulphate of zinc, diluted 
to quarter 

Iodide of potassium, 30 
gr. ; water, 850 gr 

Monohydrate sulphuric, 20 
gr. ; water, 220 gr 

Nitric acid, commercial 
(sp. w. 1.31) 

Protochloride of antimo- 
ny, 30 gr. ; water, 120 gr. ; 
and hydrochloric acid, 
100 gr 



I 


o 

'5 
a) 
P. 


1.1707 


1.1707 


1.1707 


1.1707 


1.1707 


1.1707 


1.1707 


1.1707 


1.6008 


i'44io 


1.4410 


1.4410 


1.4410 


1.4410 


1.4410 


1.4410 



g & Conductibility. 



So 



0° 

9.25 
9.25 
9.25 
13.40 
13.40 
13.40 
13.40 

13.40 

13.00 

13.00 

13.00 

13.00 
14.40 

14.40 

14.40 

12.50 

19.00 

13.10 

15.00 



100,000,000.00 

5.42 

3.47 

2.08 

31.52 

23.08 

17.48 

13.58 

10.35 
8.995 
16.208 
17.073 

13.442 

5.77 

7.13 
5.43 
11.20 



112.01 



•7. ~ 

Ik 

o.z, 

-^ 



a a 



0.0286 



0223 



Observa- 
tions. 



Maximum. 



Maximum. 



This table shows the maximum conductibilities of the solutions of nitrate of 
copper and sulphate of zinc, but not that of chloride of sodium. The maxi- 
mum conductibility of this latter is found in a mixture of 24.4 parts of chloride 
for 100 of water. 



256 



TABLES. 



IV. LIQUID RESISTANCES. 

{Table taken from Fleeming Jenkin. Calculated by Becker.) 
SULPHATE OF COPPER. 



Percentage 


of 




Temperature, Centigrade. 








salt in so 


lu- 






Observations. 




tion. 


14° 


16° 


18° 


20° 


• 24° 


28° 


30° 




8 




45.7 


43.7 


41.9 


40.2 


37.1 


34.2 


32.9 


Resistance o f 


a 


12 




36.3 


34.9 


33.5 


32.2 


29.9 


27.9 


27.0 


cubic centimetre 


16 




31.2 


30.0 


28.9 


27.9 


26.1 


24.6 


24.0 


expressed 


in 


20 




28.5 


27.5 


26.5 


25.6 


24.1 


22.7 


22.2 


ohms. 




24 




26.9 


25.9 


24.8 


23.9 


22.2 


20.7 


20.0 






28 




24.7 


23.4 


22.1 


21.0 


18.8 


16.9 


16.0 







SULPHURIC ACID— Diluted. 



Specific 
Gravity. 


0° 


4° 


8° 


12° 


16° 


20° 


24° 


28° 




1.10 


1.37 


1.17 


1.04 


.925 


.845 


.786 


.737 


.709 


Resistance of one 


1.20 


1.33 


1.11 


.926 


.792 


.666 


.567 


.486 


.411 


cubic centi- 


1.25 


1.31 


1.09 


.896 


.743 


.624 


.509 


.434 


.358 


metre to con- 


1.30 


1.36 


1.13 


.94 


.79 


.662 


.561 


.472 


.394 


duction be- 


1.40 


1.69 


1.47 


1.30 


1.16 


1.05 


.964 


.896 


.839 


tween opposed 


1.50 


2.74 


2.41 


2.13 " 


1.89 


1.72 


1.61 


1.52 


1.43 


faces expressed 


1.60 


4.82 


4.16 


3.62 


3.11 


2.75 


2.46 


2.21 


2.02 


in ohms. 


1.70 


9.41 


7.67 


6.25 


5.12 


4.23 


3.57 


3.07 


2.71 





SULPHATE OF ZINC. 



10° 12° 14° 16° 18° 20° 22° 24 



96 grammes in 100 c.c. 
of solution 



22.7 



21.4 



I ' I 



19.2 



18.1 



17.1 



16.3 



15.6 



Resistance of one 
cubic centimetre. 



The same solution ) 
with an equal vol- V 
ume of water ) 



14° 16° 



18° i 20° 



22° I 24° 

I 



21.1 20.3 19.5 18. 818. 147.3 



ill! 



Expressed in ohms. 



Nitric acid (sp. w. ) 
1.36) f 



1.94 



1.83 1.65 



10° 



1.50 1.39 1.30 1.22 

I I I 



1.18 



Resistance of one 
cubic centimetre 
in ohms. 



TABLES. 



257 



Y. DILUTE SULPHURIC ACID. 

(Bineau's Table.) 



oZ 


eight. 


Temperature — 0° Centig. 


Temperature = 15° Centig. 


ft- 




















3 >> 

KM U 
Hi" CD 




Monohydi-ate 
acid for 100 


Anhy dride 


Monohydrate 
acid for 100 


A n h y d r i de 


acid for 100 


acid for 100 


u <v V 

P 


'3 


of the mix- 


of the mix- 


of the mix- 


of the mix- 


ft 

w 


ture. 


ture. 


ture. 


ture. 


5.0 


1.060 


5.1 


4.2 


5.4 


4.5 


10.0 


1.075 


10.3 


8.4 


10.9 


8.9 


15.0 


1.116 


15.5 


12.7 


16.3 


13.3 


20.0 


1.161 


21.2 


17.3 


22.4 


18.3 


Sr5.0 


1.209 


27.2 


22.2 


28.3 


23.1 


30.0 


1.262 


33.6 


27.4 


34.8 


28.4 


33.0 


1.296 


37.6 


30.7 


38.9 


31.8 


35.0 


1.320 


40.4 


&3.0 


41.6 


34.0 


36.0 


1.332 


41.7 


34.1 


43.0 


35.1 


37.0 


1.345 


43.1 


35.2 


44.3 


39.2 


38.0 


1.357 


44.5 


36.3 


45.5 


32.2 


39.0 


1.370 


45.9 


37.5 


46.0 


38.3 


40.0 


1.3&3 


47.3 


38.6 


48.4 


39.5 


41.0 


1.397 


48.7 


39.7 


49.9 


40.7 


42.0 


1.410 


50.0 


40.8 


51.2 


41.8 


43.0 


1.424 


51.4 


41.9 


52.5 


42.9 


44.0 


1.438 


52.8 


43.1 


54.0 


44.1 


45.0 


1.453 


54.3 


44.3 


55.4 


45.2 


46.0 


1.468 


55.7 


45.5 


56.9 


46.4 


47.0 


1.483 


57.1 


46.6 


58.2 


47.5 


48.0 


1.498 


58.5 


47.8 


59.6 


48.7 


49.0 


1.514 


60.0 


49.0 


61.1 


50.0 


50.0 


1.530 


61.4 


50.1 


62.6 


51.1 


51.0 


1.546 


62.9 


51.3 


63.9 


52.2 


52.0 


1.5&3 


64.4 


52.6 


65.4 


53.4 


53.0 


1.580 


65.9 


53.8 


66.9 


54.6 


54.0 


1.597 


67.4 


55.0 


68.4 


55.8 


55.0 


1.615 


68.9 


56.2 


70.0 


57.1 


56.0 


1.634 


70.5 


57.5 


71.6 


58.4 


57.0 


1.652 


72.1 


58.8 


73.2 


59.7 


58.0 


1.671 


73.6 


60.1 


74.7 


61.0 


59.0 


1.691 


75.2 


61.4 


76.3 


62.3 


60.0 


1.711 


76.9 


62.8 


78.0 : 


63.6 


61.0 


1.732 


78.6 


64.2 


79.8 


65.1 


62.0 


1.753 


80.4 


65.7 


81.7 


66.7 


63.0 


1.774 


82.4 


67.2 


83.9 


68.5 


64.0 


1.796 


84.6 


69.0 


86.3 


70.4 


65.0 


1.819 


87.4 


71.3 


89.5 


73.0 


65.5 


1.830 


89.1 


71.2 


91.8 


74 9 


65.8 


1.837 


90.4 


73.8 


94.5 


77.1 


66.0 


1.842 


91.3 


74.5 


100.0 


81.6 


66.2 


1.846 


92.5 


75.5 






66.4 


1.852 


95.0 


77.5 






66.6 


1.85* 


100.0 


81.6 







258 



TABLES. 



VI. RESISTANCE OF DIFFERENT LIQUIDS. 



Dilute 


Sulphuric Acid after Sa- 








weljev. 




Chloride op Sodium. 


Nitrate op Potash. 


(Extract from Wiedemann.) 






-ij 








+3 05 








3 


Nag 


of . 
ST* 


© 


M 


03 T3 
©Jf> 


■ **» 

It ■ 


03-5 


s 

"3 


no ° 

s © 




| 
'55 


IS 

.22 o 


to u P 


c a 
.S2o 


a 


cS ° ,_ ' 


So 


"3 


cS^ ° 


©-H 


ce«-< ° 


Urn 


te 


fc 


H 


ti 


Ph 


M 


Ph 


tf 


1.003 


0.5 


16.1 


16.01 


25.8758 


0.59852 


18.9167 


0.&3271 


1.013 


2.2 


15.2 


5.47 


24.4033 


0.57982* 


13.7647 


1.10626 


1.053 


7.9 


13.7 


1.884 


20.9787 


0.63840 


10.4840 


1.35099 


1.080 


12.0 


12.8 


1.368 


17.0174 


0.71109 


6.6079 


1.94955 


1.147 


20.8 


13.6 


0.960 


10.4525 


1.03934 


3.3964 


3.32633 


1.190 


26.4 


13.0 


0.871 


6.0957 


1.55599 


1.5452 


6.38318 


1.215 


29.6 


12.3 


0.830 


3.6880 


2.46492 






1.225 


30.9 


13.6 


0.862 


1.7177 


5.56571 






1.252 


34.3 


13.5 


0.874 








1.277 


37.3 




0.930 


* Minimum. 






1.348 


45.4 


17.9 


0.973 
1.086 








1.393 


50.5 


14.5 




1.492 


60.6 


13.8 


1.549 




1.638 
1.726 


73.7 
81.2 


14.3 
16.3 


2.786 
4.337 


The above figures are taken from a me- 
moir of Schmidt ; Annates de Poggen- 


1.827 


92.7 


14.3 


5.320 


dorff. See Wiedemann, vol. i. p. 324. 
It is seen that the maximum conducti- 








bility or the minimum resistance of the 


The a 


bove figures show 


the max- 


sea-salt solution corresponds to 24.4 for 


imum ( 


;onductibility of 


ihe mix- 


100 of water. 


ture to 


be that of 29 to 30 


parts of 


The figures correspond to the Jacobi's 
standard of resistance, and must be mul- 


the mo 


nohydrate acid f( 


>r 100 of 


water ; 


a little different f 


rom that 


tiplied by 598 X 10 7 to be brought to elec- 


of the p 


receding table. 




tro-magnetic absolute measurements. 



Experiments Qf Horsford, 1847. (-See Wiedemann.) 

Chloride of potassium, 27. 6 grammes in 500 grammes of water 577,100 

" " diluted to half 1,103,700 

" " " quarter 2,006,500 

Chloride of sodium, 27.6 grammes in 500 grammes of water 577,100 

diluted to half 1,488,200 

Chloride of calcium, dissolved (sp. w., 1 .04) 672,560 

Chloride of magnesium 672,560 

Chloride of zinc 1,092,500 

Experiments of Wiedemann (1856) from 18° to 20° Centigrade. 

SULPHATE-OF-COPPER SOLUTION. 

31 .17 grammes in one litre of water 7.805,000 

62.34 " " 4,202,000 

77.92 " " 3,5i4,000 

93.51 " " 3.178,000 

124.68 " " 2,567,000 

155.85 " " 2.181,000 

187.02 " * " 1,936,000 



TABLES. 



259 



£iOOw 1OHWN00O1 
OOlC'* OC OS OS CD to t- 
^ O © © 660'rt'riri 



to T*csostoosco<N<>jeoeo»oicweowiQweo 2* e? © 
N iftc<<Ne»©*eoeo!ow«oiOL'-osaDosososos eo i-j « 

<?* OJ O © O O © ©' © © O ©' O ©' ©' ©' © © ©' ridrt 



IOCS IO»l»nrt« 
i— l t-i -?— I CO CO CO 



":):)if5«M»Tf#t-01HI0Oifli 



a 
as 

c3 O 






w PP< 
P'P'P 



"fig. 

©o 

1! 



aaa 

s- *- s-> 3 3 3 

&a\p< ■£"£"£ 
o o 0.2,2.2 
OOOP-iPhP-i 



g'g • a a a a a a 

~ +J 'P. 333333 



.5 o,2 S S S S S S 03^3 2 2 2 aftftaaa •§ 

■£» p^ -p -a T3 xs -C d p p o o o pppppp. t§ 

^aTodcJc3c3d(JO o^^« 000000 2 

PkA OOOOOOQQ^^i^ODOOOD Ph 



3 

: a d 
■3 2 

a-? 



o o 



ppp, j 

ppp . 

o o o • 

o o o • 



o o 0332 

CD D C °0 'o 

ta ta ta * * * 
ppp o o o 

p. ft pre c a 

pss-S^S 



caO 

pW 



as 

■CO 



3 3 
'3 '—• ±5 . eo -h 

«?^o^c.||8§<&§oS 



u <V Sh D r 



:P M 




• CUOcdD 

:££ 
: ££ 

„ -pp 

<u : fci fci •. 

O N ? £ ^ 

00770 

ea caOO ea"3 
p, a „^ K a. 1 
3 POO'S S 



O^j 



• P-P 

• tub tub 

• £ ^ 



«6d.a§ 



5 



'En- 



*E9 «w „_, 'n «w 'n 



«J) , gO^ + J) 0« 1 0«0^ j j++ 

WW 



'S'2« a;, '50'^^"c5'^*"5^-S.2' c Oo 
? '3 -2 S P ji< '? "S P '? ^^"^ °Tc '5 a m 



tffSJjpy 

Offl 



5^^oq5S^o^c»S<j^6co§ 



2o 

1"S 

<*P 
O Pi 

!"§ 
•s*.a 

ccft 



6 

s 
sS 

of 

fell 



: : : : ca^ ■ ■ 

« y o o-w ,J © 

.s.s.s.s o t^ .a 
n'n n'n p,t- a n 

■a-s °S|-Ja 

a|| 
■.sagaas-a§a 



aaaaa 

c3 03 o3 cs c3 



c3 ea 

aa 

ca ca 
tx tn 



aa 

ea eS 
txcx 



oooo22oooooooooo22 

nSSnj^nSSnn n n n n n < < 



SIN 



£ o 



260 



TABLES. 



VIII. ELECTRO-MOTIVE FORCES. 

(Poggendorff, 1845. — Extract from Wiedemann) 
SINGLE-LIQUID BATTERIES. 



Zinc 

Tin .. 

Zinc 

Iron 

Zinc 

Zinc 

Cadmium 

Amalgamated zinc. 
Amalgamated zinc. 



Sulphuric acid (sp. w. = 1.838) 
diluted with 49 times its weight 
of water 



Daniell : 
Tin ... . : . 

Copper 

Copper 

Copper — 

Silver 

Cadmium . 

Iron 

Iron ....... 

Tin 

Copper 

Platinum . 

Copper 

Platinum. . 
Platinum. . 
Platinum. . 

Iron 

Silver 

Platinum . 
Antimony . 

Iron 

Copper 

Platinum. . 

Copper 

Iron 

Copper 

Platinum. . 
Copper — 



Amalgamated zinc. 
Amalgamated zinc. 



Nitric acid (sp. w. = 1.22) diluted ) 
with 9 times its w'ght of water f 



Amalgamated zinc. 
Amalgamated zinc. 

Copper, 

Silver 

Zinc -. 

Zinc 

Zinc 

Zinc 

Zinc 

Zinc 

Zinc 

Iron 

Zinc 

Zinc 

Zinc 

Iron 



(Hydrochloric acid (sp. w. =1 . 113), 
diluted with 9 times its weight 
of water 

1 

I Potash in 6 times its weight of 
water 

Carbonate of potash 

S Carbonate of potash, concen- 
trated 

Choride of potassium 

(Chloride of potassium, concen- 
C trated ; . . . 



TWO-LIQUID BATTERIES 





Iron. 


r 


Iron. 
Zinc. 




Zinc. 




Zinc. 


Grove.. . - 


Zinc. 




Zinc. 




Zinc. 

Zinc 

i Zinc. 




Zinc. 


Daniell . - 

1 
{ 


Zinc 
Zinc. 
Zinc. 
Zinc. 



S0 3 HO + 49HO by 

weight 

Sulphuric acid 

Sulphuric acid 1, 

water 4 

Sulphuric acid 1, 

water 4 

Sulphuric acid 1, 

water 12 

Sulphuric acid 1, 

water 4 

Sulphuric acid 1, 

water 12 

Sulphate of zinc . . . 

Sea-salt, NaCl 

Sulphuric acid 1, 

water 4 

Sulphuric acid 1, 

water 12 

Sea-salt 1, water 4 . 

(_ Bichromate of J 
f potash 3. I 



Sulphate of copper. 
Nitric acid 

Nitric acid, fuming. 

" (sp.w.1.33) 

" (sp.w.1.33) 

" (sp.w. 1.19) 

'• (sp.w. 1.19) 
" (sp.AV. 1.33) 
" (sp.AV. 1.33) 

I Sulphate of cop- 
> per, concen- 
trated 

J I 

(Sulphuric acidj 
f 4, water 18.... | 



Copper. .. 
Platinum. 

Platinum. 

Platinum. 

Platinum. 

Platinum. 

Platinum. 
Platinum. 
Platinum. 

Copper. .. 



Copper. .. 
Copper. . . 
Copper. . . 
Carbon . . 
Platinum. 



TABLES. 



261 












= 


E 


S 



© © © 4} 

ft ft a Prj3 • 
o o o oA^, . 

OOOOaftPn 



'o3 o3 o3 



fcn t, f* U 

ft ft ft ft 
ftftftft 
O O O O 

© © © y 



o o o O'd'd'd 
© © © ©'3 '5 '3 
"§ a "c3"o3 tf e3 tf 
,s.s.fi,3 o © © 
ft ft ft ft'E -fi '£ 



3§ 

§5 



© rf 



a 3 <3l3 Stf o 



N S n'n N N N 

-d -a -d -d -a -c -d 
©©©©©©© 

-u -u _ += ,- .u -u 
o3 o3 c3 o3 o3 o3 o3 

aaaaaaa 

o3 o3 o3 o3 o3 o3 o3 
13 13 "5 13 13 13 "3 

ESHHSSS 



t- i.- OS L- OS 



£ 



S 



s o .-3 o 

<3 3 O £ 2 



© 

3 

© © © © „ 

o3 o3 o3 o3-S 
© © © © 9 



■d 'd'd'd *d 



© © © © © 
'E "fi "C "2 's 

ftftftftft 



© © © © © 

.S.S.S.S.S 



o3 o3 o3 c5 o3 

aaaaa 

c3 c3 c3 c3 c3 
fcX fcJD tX fcjD 6b 

c3 c3 c3 c3 ctf 

aaaaa 



S 



c: — < ~ :~ C X 

i': w i - c -f 



a 

£ 0.3 S a ^ 

•S ^ ^ ^ ft ft 

"2 u to u ft ft 
,3 c3 e3 rt o O 

ft O O ^ o ^ 



© © 

3 aa 

Eoo 

[ddd 3 ° ° 
'©'©'© o®® 
* « s '3 o3 03 
© © © ^_AA 

E - sa p ft a 



-d'd'd'd'd'd 



_© © u © © o 
aaaaap, 

33S3S3 

CO CO CO CO CO CO 

©©©©©© 

:3?3S? 



© © © © © J; 

2 a 3 3 a 3 

-ddd-d-d-s 

© © © © © » 

03 o3 o3 o3 o3 2 

aaaaa^ 

o3 o3 o3 o3 o3 O 
jBftfif 1 Jf ft £l if s 

o3 o3 o3 o3 c3 o 

aaaaa! 

<^<M<1S1 



© © 2 « 3 .3 

£3«S © 03 © 

CSCftP,^ 



•OOlSOJW 



s 



N 



v. 



:aaaaaaaa 

s*33333323 

a..s .a .a .a .a .a .a .a 

rt 13 "ol H "o3 rt rt "o3 
H "ft 



ft- >v 

OftftftftPnpH 



:-d1liJ'§l 
g/ :'S«.2.3 a © © 

g< .oS-g-C-dp-r-c 

'Sdo'So'S-IS 

J§ og-C-E-S *«® 



^ ■- £>j2 a £ ^ 5 3 



-d -d d -d d -d -d d 



©©©©©©©©^ 

32333333^ 
,3 ,3 J5 ,3 ^ ^= J5 X <,_, 

ft ft ft a ft cap, o 

3 2 3 3 3 3 3 3© 

C0C0CCC0CC7JCOK+^ 

©©©©©©©©S 
+J « 4J « +J +J +J 4- -2 

3 3 3 3 3 3 3 3» 



N N N N S3 S3 N N SI 



© © 

go 

c3 u 



262 



TABLES. 






£ 1 



US 



H 

O 

6 1 

M | 

l— l s 



CD CO lO 7-1 00 ! 
OOOOOl 



oooMS cS 
OOOOP-iOO 



t| ^ Sj ^ 

a; a) © © 

ftftftft 
ftftftft 
0000 
0000 



0000 S22 

05 05 05 05 '3 '3 '3 
+3+3-1^+3 ce cfi cS 



> > 

88 

•d-d 

3 3 



O O 05 05 

22** 

CO 02 02 02 



3*,3 
■3 '3 '3 

000 
"2 '£ 'C 

,3,3-3 
ft ftft 

05 05 05 

3 3 3 



: a : a : : ,: 

N © N J n"E3 N 

*-£*"£*** 

« 2_05 ™ 05 05 05 
o3 ^ c3 S s3 o3 o3 



1 » i * i 
a s a a a a a 



S-i 3 



.a 

l 






100 
00 






St5 ; 



.2 -a 05 

3 p &o 

w *a2 

3fi^? 

33 05.3 

— Scf 

a '3 

3 05 05 

^*£ 

S3S 
Oj 05 O 

6ft3 ' w 

jpM 



OOsC 



rtOrt THrtrlrl 



o 

3 

:* 

■ 3 
: * 

3 3 3 3 
g0505 SOOO 
ftftft X5jDj2jO 
ftftft tl'S'S'S 
OOO <& c3 c3 e3 
OOO OOOO 



3 3 
I"! 



?? "t-i ! • ! '. 
33 • J. • 05 lao 

-S-S -.2 --^ • SCI 



•3 :is 



05 

. T-l +3 



i &x>; 



I o 3 (£, 



s 

£ OJO 
.3 



s| 



0)0)^0 

ftft05 g 

ftftftp,- 

O O ft 
C5 O 0(m 

oo w hoS* „* 

s3 c3 05 e8 

ftftS ft 



o2&£ 



3 ra 
,3 o 



05 05 05 05 

+3+3+3 43 

o3 oi c3 o3 



0000 
"E "C "fi *<3 
3 3 3 3 
,3,3,3,3 
ftft ft ft 



«» : 



a * * ,3 -a -3 
§•3 o .2 3-3 

•g c3 o3,3 3 ce 

a - c-E*w-c 

3 3 ST"' -1 3 
°3 ftft-^-S ft 



33 "S'33^ s3 ' 



Co c^ o3 ci 

aaas 

c3 c6 c3 ^ 



aaaa saaa 



N N N N N 

4? 05 05 05 05 

-u +3 -u +j 43 

c3 c3 c3 c3 ci 

asaa a 

co Cj ^ c5 <s$ 

6jd 6£i sib 6b tii 



I 3 



TABLES. 



263 



ooofflCioac.xoNtot-NL-i-i-aaoco »o «■ -^ -gi 0100 co « c* ->? 



22222 :§S :g . 

S.S,aa^-I.S|.|o.?flo.?o.jooo 

§•§•§■§•§•§•.5.5.3 « * § £* £ § § « s § is 

OOOOOOftPHftP-iP-iOOftUOOft:0 00 



o3 c3 



o 

fc > c3 ^ 

£ ft & <$ 
S cefio 



Qs 



bo T 



P3 3 

3 3 

— — 

o3 03 

x x 

o o^ o o 03^^-33:22333 2222 2 

tits ©tststs «§§§«*««« «.2 * « «3 .2 
.cs'SftftftooooooooooSoooC 

ftftu ft ft ftC £ "£ '2 '£ "S 'u '£ '£ "E g '2 "fi "E g 













1 
1 


£ 
i 


Ob 

5 


00 ; 

CO . 

f! 



*2 

x ft. 



:/2 : 
• 3 • 

D 03 0) 



ftOft 

ill 

i<d fta> 

S3S 



<d-3 c 
> 03 -3 
ft <»«. 

03~<g 

3 * O 
Eftft 
© ftp 



tf'eS'c! 



2 :*: 



a* 



-d -a ■co .5 '-3 d 



©©'©' 
u u u 

<X> Oy <P 
~o! o3 o3 



O 1-1 ' 



CJ 3} Q} £> D 
tl "el "e! "si "o3 



«S<w 



3-S333'd'd'C , c333S.^ 
o n o '3 '5 '5 "3 "5 - 3 '5 o '3 "3 '3 



0000 



S 



333 
ftftft 



•5 5 
3 033 

ftft E 
ftfto 

= 3^ 
CCCOO 



"5 ? 

g-d 

3 13 

X! X 



OOOJOJOOOO 7* 



3 n"3'3' 

a3 cm c3 o3 

2 a) -2 -2 .2 .2 .2 .2 .2 -2 .2 .2 .2 • 

33"c333333333333^ 
.3,3,3,3,3,3,3,3,3,3,3,3,3,3 

3333 ^333333333 
'333333333's3333 
cococctocotocGcococoaicccea! 



2 :S 

c3 • ©3 



o ; o 
3 . 3 

o :o 



3 ; 3 



o :*o 

03 • 03 

-3 u '-3 



;d 

3 3 o3 • i8 

■ n NSri 3-d 
; <h *£ S *3 3 '" 
• ° ° 3 03 3 < 



3 ° ^ "d,; 00 3 03 3 03 

® ^3 2 fl 2 S^-a 3 3 3 3 

3 3 5 §3 2ftft|^|^ 

fi CO CC 02 COX^ F 



.S .S .5 -S -a -S .S .5 •£ -S -S .S .£ .5 .5 .5 .5 .5 .2 

*n 'n '5 ^ ^ 'n "n *n 'n "n 'n "S "n "n 'S 'n '3 '5 "S 

'3'3'3'S"tj'3'3'3'3'3'3'3'0'3'3'3'3'3'3 

O3o3o3t33o3o3o3e3o3o3o3o3o3o3o3o3o3o3 

S2S,|^222222222S2222 

bC tCbC 2 S bJD &JC' bJC b£ b£ b£ bi fcJO &JD fcX b£ bJD ti fcJD 

SS2asa222222H222222 
<} «1 <3 1> p «5 <} <! <j «< «j «! <3 «}«! <1 <$ <j «3 



3 d 3 

3 3 3 




03 08 > x o3 tuO> to 

Sft o 3S tJOO 3 

3si«3cjO« 3 

MOOWOW fQ 



fi fi 



3 23 
<U 3 S 

Mficc 



REMARKS UPON THE PRECEDING TABLES. 



It is seen that the Daniell battery may be superior 
or inferior to the volt, according to the proportions of the 
mixture of sulphuric acid and water in which the zinc is 
immersed. 

The conclusion to be drawn is that, for a certain com- 
position of this mixture, the electro-motive force of the 
Daniell is equal to the volt. Consequently, except for 
researches requiring great precision, the English unit 
(volt) and the Daniell may be indifferently used. 

The figures given by different observers disagree, as is 
seen from the tables ; these differences may arise from 
various causes, of which the principal is, no doubt, the 
difference of composition of the mixture in which the 
zinc is immersed. The table shows that the electro-motive 
forces of DanielPs and Grove's battery vary with the pro- 
portions of the mixture of sulphuric acid and water. It 
seems as if there might be made a very interesting study 
upon this question, searching, for instance, the conditions 
of the maximum electro-motive force of an element. 

We conclude our tables with secondary batteries having 
electrodes of platinum and of lead (Plante). The ques- 
tion of finding out the maximum force of polarization of 
a voltameter has been studied by several physicists, and 
it does not seem to have been definitely decided upon. 
The figures which we give are those of Wheatstone, who 
was the first to undertake to determine it. 



COXCLUSIOIT 



In the preceding chapters we have studied hydro-electric 
batteries ; that is, apparatus capable of producing electric 
currents by means of chemical energy. They are there- 
fore contrivances which transform chemical action into 
electricity. 

Thermo-electric batteries, of which we have not spoken, 
are contrivances which transform heat into electricity. 
The v have made very important progress of late years, 
and everything leads to the belief that before long they 
will be of great service to industry, whereas up to this 
time they have only been of interest to physicists. 

These two kinds of apparatus are not the oniy ones by 
which electricity may be produced ; there are to be cited 
frictional electrical machines, electrophori, and machines 
like those of Holtz. 

But another category, that of magneto-electric machines, 
has lately assumed a rapidly increasing importance. Enor 
mous progress has been made, notably by Gramme, which 
has led to the construction of machines of unprecedented 
power. 

These machines, frictional machines, machines of Holtz, 
magneto-electric machines, are all contrivances which 
transform movement into electricity, and should, there- 
fore, be classed together. 

It appears certain that all the apparatus producers of 
electricity that will hereafter be invented will be com- 



266 conclusion. 

prised in one of these three classes ; in other words, it 
does not seem possible to produce electricity without ex- 
pending chemical energy, heat, or movement, because en- 
ergy only presents itself under these four forms. 

Hydro-electric batteries have of late years made less 
progress than the apparatus of the other two categories, 
but they are still open to improvement, and will eventually 
make important progress. 

First of all, the exact nature of the chemical reactions 
which take place in these batteries must be elucidated ; it 
is disgraceful that at the present time it is not known ex- 
actly what goes on in Grove's or Bunsen's battery. 

The extremely small but incontestable variations in 
the electro-motive force of even completely depolarized 
batteries, such as that of Daniell, must be explained. 

The variations in the internal resistance must be studied, 
variations which are but incompletely explained by the 
change in the chemical composition of the liquids. 

Finally, new reactions among the infinite number pre- 
sented by chemistry must be used, and above all zinc must 
be dispensed with, which has hitherto thrust itself, so to 
speak, upon inventors. 



£&*:. 



HIM R - 1951 



III! 











B> ^ 



**, 






^> ♦OKO' ,v. C 
























*++ & 






,- ^ \ 









S\ 






- - 

-I <p 






























V ^ 





















■ 



' 









$o 






